CN116367248A

CN116367248A - Communication method and device

Info

Publication number: CN116367248A
Application number: CN202210114805.3A
Authority: CN
Inventors: 窦凤辉; 王志峰; 金辉; 薛祎凡
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-12-28
Filing date: 2022-01-30
Publication date: 2023-06-30
Also published as: WO2023124992A1

Abstract

The application provides a communication method and a communication device, which relate to the technical field of wireless communication and can enable terminal equipment to switch, redirect or reselect between an equivalent public land mobile network EPLMN and a home public land mobile network HPLMN so as to shorten or eliminate service transmission interruption time and improve user experience. The method comprises the following steps: the method comprises the steps that first access network equipment obtains HPLMN information of terminal equipment, wherein the first access network equipment is access network equipment in a PLMN to which the terminal equipment is currently accessed, and the PLMN to which the terminal equipment is currently accessed is different from the HPLMN of the terminal equipment. The first access network device sends first information to the terminal device according to the HPLMN information of the terminal device, wherein the first information relates to the HPLMN of the terminal device, and the first information is used for measurement, HPLMN searching or reselection of the terminal device.

Description

Communication method and device

The present application claims priority from the chinese patent application filed at 28 of 12 months 2021, filed with the national intellectual property office under application number 202111627665.1, application name "a method of mobility management, UE and network device", the entire contents of which are incorporated herein by reference.

Technical Field

The embodiment of the application relates to the field of wireless communication, in particular to a communication method and device.

Background

The network coverage conditions of different network operators in different regions are different. For example, in a remote area of china, the network of the mobile operator of china has coverage, and the network of the operators of china telecommunication or china communication is not covered. In this case, the china mobile operator provides a shared network for other network operators such as china telecom or china Union, so as to enable terminal devices of the other network operators to access.

Disclosure of Invention

For terminal devices of other network operators such as china telecom or china Unicom, a series of problems such as handover are involved in the case that the terminal device moves between its home network coverage area and the shared network coverage area. How to provide a handover method between a shared network and its home network is a problem to be solved.

The embodiment of the application provides a communication method and a communication device, which can enable terminal equipment to switch, redirect or reselect between a shared network and a home network so as to shorten or eliminate service transmission interruption time and improve user experience.

In order to achieve the above purpose, the embodiment of the application adopts the following technical scheme:

in a first aspect, the present application provides a communication method, where the implementation body of the method may be a first access network device, or may be a chip applied in the first access network device. The following describes an example in which the execution body is a first access network device. The method comprises the following steps: the method comprises the steps that first access network equipment obtains Home Public Land Mobile Network (HPLMN) information of terminal equipment, wherein the first access network equipment is access network equipment in a current access PLMN of the terminal equipment, and the current access PLMN of the terminal equipment is different from the HPLMN of the terminal equipment. Then, the first access network device sends first information to the terminal device according to the HPLMN information of the terminal device, wherein the first information relates to the HPLMN of the terminal device, and the first information is used for measurement, HPLMN searching or reselection by the terminal device.

Thus, after the first access network device acquires the HPLMN information, it can be determined that the terminal device is in a roaming state, and then the first information is sent to the terminal device. Since the first information is related to the HPLMN of the terminal device, when the terminal device performs measurement based on the first information, heterogeneous network measurement can be performed, which lays a foundation for the terminal device to switch or redirect from the currently accessed PLMN to the HPLMN. When the terminal equipment searches the HPLMN based on the first information, the frequency points in the HPLMN can be searched, a measurement report of the different network is generated, and the base is laid by switching or redirecting to the HPLMN. When the terminal equipment reselects based on the first information, the terminal equipment can reselect from the current access PLMN to the HPLMN to normally perform service transmission because the first information is related to the HLMN, thereby being beneficial to improving user experience.

In one possible design, the first information indicates that the HPLMN searching for the terminal device is initiated to cause the terminal device to switch (or redirect, or reselect) to the HPLMN in a timely manner.

In one possible design, the first information includes a cell selection policy. The cell selection policy is also related to the current access of the terminal device to the PLMN, and the measurement configuration information is used for the terminal device to reselect.

In one possible design, the cell selection policy indicates that the first priority is higher than the second priority. The first priority is the reselection priority of the first cell in the HPLMN of the terminal equipment, and the second priority is the reselection priority of the second cell in the PLMN to which the terminal equipment is currently accessed, so that the terminal equipment reselects to the HPLMN in time.

In one possible design, the first information includes measurement configuration information. The measurement configuration information comprises information of frequency points in the HPLMN of the terminal equipment and information of measurement interval duration of the frequency points. The measurement configuration information is used by the terminal device to determine on which time domain resource(s) to measure the HPLMN intermediate frequency point.

In one possible design, the frequency point in the HPLMN of the terminal device includes at least one of: the frequency point of the first communication system in the HPLMN of the terminal equipment or the frequency point of the second communication system in the HPLMN of the terminal equipment. Wherein the first communication system is different from the second communication system. Illustratively, the first communication scheme may be a 5G network, and the second communication scheme may be a 4G network, a 3G network, or a 2G network. Alternatively, the first communication scheme may be a 4G network and the second communication scheme may be a 3G network or a 2G network. Alternatively, the first communication scheme may be a 3G network and the second communication scheme may be a 2G network.

That is, the measurement configuration information may configure the frequency points of at least two communication systems in the HPLMN, so that the terminal device may search and measure the frequency points of at least two communication systems in the HPLMN, so that the terminal device switches (or redirects or reselects) to a communication system network with a better measurement result, so as to achieve better data transmission performance.

In one possible design, the first access network device obtains home public land mobile network HPLMN information of the terminal device, including: the first access network device receives a first message from a first core network device, wherein the first message includes HPLMN information of the terminal device, and the first core network device is the core network device in the PLMN to which the terminal device is currently connected, so that the first access network device perceives the HPLMN information of the terminal device.

In one possible design, the first message includes an initial context setup request message.

That is, the first access network device may obtain HPLMN information in the registration procedure.

In one possible design, the first access network device obtains home public land mobile network HPLMN information of the terminal device, including: the first access network equipment receives a second message from the terminal equipment, wherein the second message comprises information of the current access PLMN of the terminal equipment, and a corresponding relation exists between the current access PLMN of the terminal equipment and the HPLMN of the terminal equipment. And the first access network equipment determines HPLMN information of the terminal equipment according to the second message and the corresponding relation.

In this way, the terminal device reports the information of selecting to access the PLMN to the first access network device, and the first access network device can perceive the HPLMN information of the terminal device based on the information of the current access of the terminal device to the PLMN and the corresponding relation.

In one possible design, the first access network device obtains home public land mobile network HPLMN information of the terminal device, including: the first access network device receives a third message from the terminal device, wherein the third message includes HPLMN information. That is, the terminal device directly reports the HPLMN information to the first access network device, so that the first access network device perceives the HPLMN information of the terminal device.

In one possible design, the communication method of the embodiment of the application further includes: the first access network device sends a fourth message to the second access network device, wherein the fourth message comprises HPLMN information of the terminal device, the first access network device is the access network device before terminal device switching, the second access network device is the access network device after terminal device switching, the second access network device and the first access network device belong to the same PLMN, the fourth message is used for the second access network device to send second information based on the HPLMN information of the terminal device, the second information is related to the HPLMN of the terminal device, and the second information is used for terminal device measurement, HPLMN searching or reselection.

In this way, even if the terminal device moves in the current access PLMN, the first access network device can send HPLMN information to the second access network device when the second access network device provides services to the terminal device after the movement, so that the second access network device determines information related to the HPLMN, thereby enabling the terminal device to switch (or redirect or reselect) to the HPLMN in time.

In one possible design, the communication method of the embodiment of the application further includes: the first access network device sends a handover request (handover required) message to a first core network device, wherein the first access network device is the access network device before the terminal device is handed over, and the first core network device is the core network device in the PLMN to which the terminal device is currently connected. And the first core network equipment sends HPLMN information of the terminal equipment to the second access network equipment according to the switching requirement information, wherein the second access network equipment is the access network equipment after the terminal equipment is switched. And the second access network equipment sends second information to the terminal equipment according to the HPLMN information of the terminal equipment. Wherein the second information is related to the HPLMN of the terminal device, the second information being used for measurement, HPLMN search or reselection by said terminal device. The handover required message may be as specified in the 3GPP related technical specifications and will not be described in detail here.

In this way, even if the terminal device moves in the current access PLMN, the first core network device can send HPLMN information to the second access network device in the case where the second access network device provides services to the terminal device after the movement, so that the second access network device determines third information related to the HPLMN, thereby enabling the terminal device to switch (or redirect or reselect) to the HPLMN in time.

In one possible design, the handover required message includes HPLMN information for the terminal device.

In this way, even if the terminal device moves in the current access PLMN, the first access network device can send HPLMN information to the second access network device through the first core network device in the case that the second access network device provides services to the terminal device after the movement, so that the second access network device determines information related to the HPLMN, thereby enabling the terminal device to switch (redirect or reselect) to the HPLMN in time.

In one possible design, the communication method of the embodiment of the application further includes: the first access network device receives a measurement report from the terminal device, wherein the measurement report is determined based on the measurement configuration information. The first access network device sends a first message to the terminal device, wherein the first message indicates the target cell. The target cell is determined based on the measurement report and priority information, the target cell belongs to a cell in the HPLMN of the terminal device, the priority information indicates that a third priority is higher than a fourth priority, the third priority and the fourth priority are both handover priorities or redirection priorities, the third priority is a priority of the cell in the HPLMN of the terminal device, and the fourth priority is a priority of the cell in the current access PLMN of the terminal device.

That is, the first access network device also refers to the priority information when deciding the target cell. Since the priority information indicates that the priority of the cell in the HPLMN is higher than the priority of the cell in the PLMN to which the terminal device is currently accessing, the terminal device is also able to switch or redirect to the HPLMN preferentially.

In a second aspect, the present application provides a communication method, where the execution body of the method may be a terminal device, or may be a chip applied in the terminal device. The following describes an example in which the execution subject is a terminal device. The method comprises the following steps: the terminal equipment receives first information from access network equipment of a first Public Land Mobile Network (PLMN), wherein the first PLMN is a PLMN which is currently accessed by the terminal equipment, the first information is used for determining to search for a second PLMN by the terminal equipment, and the first PLMN is different from the second PLMN. The terminal device searches for and resides in the second PLMN based on the first information.

Therefore, for the terminal equipment currently accessed to the first PLMN, the first information can enable the terminal equipment to determine the time for searching the second PLMN, so that the terminal equipment can timely search the second PLMN, the first PLMN currently accessed resides in the second PLMN, the service transmission interruption time is shortened or eliminated, normal transmission of the service is ensured, and the user experience is improved.

In one possible design, the first PLMN comprises an HPLMN of the terminal equipment and the second PLMN comprises an equivalent public land mobile network EPLMN of the terminal equipment.

In one possible design, the communication method of the embodiment of the application further includes: the terminal device receives second information from the core network device of the first PLMN, wherein the second information includes area information covered by the second PLMN. The terminal device searches and resides in a second PLMN according to the first information, and comprises: and the terminal equipment determines the area where the terminal equipment is positioned according to the position area where the access network equipment is positioned and the second information, wherein the first information comprises the information of the position area where the access network equipment is positioned. Searching for and camping on the second PLMN when the terminal equipment is in the area indicated by the second information.

In this way, under the condition that the first PLMN is the HPLMN of the terminal equipment, the terminal equipment judges whether the terminal equipment is in the coverage area of the EPLMN or not based on the location area of the access network equipment in the HPLMN, if so, the terminal equipment searches the EPLMN in time, so that the terminal equipment stays in the EPLMN from the HPLMN in time, the occurrence probability of the network dropping problem is reduced, the service transmission interruption time is shortened or eliminated, and the user experience is improved.

In one possible design, the area in the second information includes at least one of: an overlap region, a boundary region, or a first region. The overlapping area is an area where a service area of the core network device overlaps with a coverage area of the second PLMN, the boundary area is an area where a distance between the overlapping area and a boundary of the overlapping area is smaller than a first threshold, and the first area is an area where a distance between the boundary area and the terminal device is smaller than a second threshold.

In one possible design, the terminal device is located within the boundary region, or the terminal device is located outside the boundary region.

In one possible design, the terminal device receives the second information from the core network device through an attach accept message, so that the terminal device obtains the second information during the attach process. For the terminal equipment, the terminal equipment can timely judge whether the terminal equipment is in the area indicated by the second information based on the area where the access network equipment is located in the HPLMN, so that the terminal equipment is resided in the EPLMN from the HPLMN which is accessed currently in time, the occurrence probability of the network dropping problem is reduced, and the service transmission interruption time is shortened or eliminated.

In one possible design, the second information is transmitted via a tracking area update TAU accept message, so that the terminal device obtains the second information during the TAU procedure. For the terminal equipment, the terminal equipment can timely judge whether the terminal equipment is in the area indicated by the second information based on the area where the access network equipment is located in the HPLMN, so that the terminal equipment is resided in the EPLMN from the HPLMN which is accessed currently in time, the occurrence probability of the network dropping problem is reduced, and the service transmission interruption time is shortened or eliminated.

In one possible design, the second information is transmitted through a user equipment configuration update message, so that the terminal equipment acquires the second information in the configuration update process. For the terminal equipment, the terminal equipment can timely judge whether the terminal equipment is in the area indicated by the second information based on the area where the access network equipment is located in the HPLMN, so that the terminal equipment is resided in the EPLMN from the HPLMN which is accessed currently in time, the occurrence probability of the network dropping problem is reduced, and the service transmission interruption time is shortened or eliminated.

In one possible design, the first PLMN comprises an EPLMN of the terminal equipment and the second PLMN comprises an HPLMN of the terminal equipment.

In one possible design, the communication method of the embodiment of the application further includes: the terminal device receives second information from the core network device of the first PLMN, wherein the second information indicates at least a partial coverage area of the first PLMN, and the partial coverage area of the first PLMN belongs to a boundary area of the first PLMN. The terminal device searches and resides in a second PLMN according to the first information, and comprises: and the terminal equipment determines the area where the terminal equipment is positioned according to the position area where the access network equipment is positioned and the second information, wherein the first information comprises the information of the position area where the access network equipment is positioned. Searching for and camping on the second PLMN when the terminal equipment is in the area indicated by the second information.

In this way, under the condition that the first PLMN is the EPLMN of the terminal equipment, the terminal equipment judges whether the terminal equipment is in the boundary area of the EPLMN or not based on the position area of the access network equipment in the EPLMN, if so, the terminal equipment searches the HPLMN in time, so that the terminal equipment is switched to the HPLMN from the currently accessed EPLMN in time, the occurrence probability of the network dropping problem is reduced, the service transmission interruption time is shortened or eliminated, and the user experience is improved.

In one possible design, the partial coverage area of the first PLMN includes at least one of: an overlap region, or a first region. The overlapping area is an area where a service area of the core network device overlaps with a boundary area of the first PLMN, and the first area is an area where a distance between the overlapping area and the terminal device is smaller than a second threshold.

In one possible design, the second information is transmitted via a registration acceptance message, so that the terminal device obtains the second information during the registration process. Therefore, the terminal equipment can judge whether the terminal equipment is in the area indicated by the second information or not on the basis of the area where the access network equipment is located in the first PLMN in time, so that the terminal equipment resides in the second PLMN in time from the first PLMN which is accessed currently, the occurrence probability of the network dropping problem is reduced, and the service transmission interruption time is shortened or eliminated.

In one possible design, the terminal device searches for and camps on the second PLMN based on the first information, including: and the terminal equipment searches and resides in the second PLMN according to the second PLMN information, wherein the first information comprises the second PLMN information.

That is, the first information sent by the access network device in the first PLMN includes the second PLMN information, that is, the different network information, so that the terminal device searches for and resides in the second PLMN, thereby reducing the occurrence probability of the network drop problem, shortening or eliminating the service transmission interruption time, and improving the user experience.

In one possible design, the terminal device receives the first information from the access network device via a system message (system infomation) to enable the terminal device in an idle state to obtain the first information to search for and camp on the second PLMN in time. The system message may refer to a specification in the 3GPP related technical specification, and will not be described herein.

In one possible design, the system message carries the first information through a system information block, SIB, wherein the SIB includes at least one of: a first SIB, a second SIB, or a third SIB.

The first SIB is an SIB for carrying common frequency information, the common frequency information includes frequency point information in the second PLMN, and a frequency point in the common frequency information is the same as a frequency point of a cell where the terminal device currently resides. The first SIB may be SIB3 specified in the 3GPP related technical specification, for example.

The second SIB is an SIB for carrying inter-frequency information, the inter-frequency information includes frequency point information in a second PLMN, and a frequency point in the inter-frequency information is different from a frequency point of a cell where the terminal device currently resides. The second SIB may be SIB4 specified in the 3GPP related technical specification, for example.

The third SIB is an SIB for carrying inter-system information, where the inter-system information includes information of a communication system of the second PLMN, and the communication system of the inter-system information is different from a communication system of a cell in which the terminal device currently resides. The third SIB may be SIB5 specified in the 3GPP related technical specification, for example.

In a third aspect, the present application provides a communication apparatus, which may be the first access network device in the first aspect or any one of the possible designs of the first aspect, or a chip implementing the function of the first access network device; the communication device comprises corresponding modules, units or means (means) for realizing the method, and the modules, units or means can be realized by hardware, software or realized by executing corresponding software by hardware. The hardware or software includes one or more modules or units corresponding to the functions described above.

The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit is configured to obtain HPLMN information of a home public land mobile network of the terminal device, where the communication apparatus is an access network device in a PLMN to which the terminal device is currently connected, and the PLMN to which the terminal device is currently connected is different from the HPLMN of the terminal device. And the processing unit is further used for controlling the sending unit to send first information to the terminal equipment according to the HPLMN information of the terminal equipment, wherein the first information is related to the HPLMN of the terminal equipment, and the first information is used for the terminal equipment to perform measurement, HPLMN searching or reselection.

In one possible design, the first information indicates that the HPLMN of the terminal device is started to search.

In one possible design, the cell selection policy indicates that the first priority is higher than the second priority, wherein the first priority is a reselection priority for the first cell in the HPLMN of the terminal device and the second priority is a reselection priority for the second cell in the PLMN to which the terminal device is currently accessing.

In one possible design, the first information includes measurement configuration information. The measurement configuration information comprises information of frequency points in the HPLMN of the terminal equipment and information of measurement interval duration of the frequency points. The measurement configuration information is used for the terminal device to perform measurement.

In one possible design, the frequency point in the HPLMN of the terminal device includes at least one of: the frequency point of the first communication system in the HPLMN of the terminal equipment or the frequency point of the second communication system in the HPLMN of the terminal equipment. Wherein the first communication system is different from the second communication system.

In one possible design, the processing unit is configured to obtain home public land mobile network HPLMN information of the terminal device, and includes: the processing unit controls the receiving unit to receive a first message from a first core network device, wherein the first core network device is a core network device in a PLMN to which the terminal device is currently connected, and the first message includes HPLMN information of the terminal device.

In one possible design, the processing unit is configured to obtain home public land mobile network HPLMN information of the terminal device, and includes: and the receiving unit is used for receiving second information from the terminal equipment, wherein the second information comprises information of the current access PLMN of the terminal equipment, and a corresponding relation exists between the current access PLMN of the terminal equipment and the HPLMN of the terminal equipment. And the processing unit is used for determining the HPLMN information of the terminal equipment according to the second information and the corresponding relation.

In one possible design, the processing unit is configured to obtain home public land mobile network HPLMN information of the terminal device, and includes: the processing unit is configured to control the receiving unit to receive a third message from the terminal device, where the third message includes HPLMN information of the terminal device.

In one possible design, the sending unit is further configured to send a fourth message to the second access network device, where the fourth message includes HPLMN information of the terminal device, the communication apparatus is the access network device before the terminal device is switched, the second access network device is the access network device after the terminal device is switched, the second access network device and the communication apparatus belong to the same PLMN, the fourth message is used for the second access network device to send second information based on the HPLMN information of the terminal device, the second information is related to the HPLMN of the terminal device, and the second information is used for the terminal device to perform measurement, HPLMN search or reselection.

In one possible design, the sending unit is further configured to send a handover request message to a first core network device, where the communication device is an access network device before the terminal device is handed over, and the first core network device is a core network device in a PLMN to which the terminal device is currently connected. The switching request message is used for the first core network device to send the HPLMN information of the terminal device to the second access network device according to the switching request message, wherein the second access network device is the access network device after the terminal device is switched, the HPLMN information of the terminal device is used for the second access network device to send second information based on the HPLMN information of the terminal device, the second information is related to the HPLMN of the terminal device, and the second information is used for the terminal device to measure, search or reselect.

In one possible design, the receiving unit is further configured to receive a measurement report from the terminal device, wherein the measurement report is determined based on the measurement configuration information. And the sending unit is further used for sending a first message to the terminal equipment, wherein the first message indicates the target cell switched or redirected. The target cell is determined based on the measurement report and priority information, the target cell belongs to a cell in the HPLMN of the terminal device, the priority information indicates that a third priority is higher than a fourth priority, the third priority and the fourth priority are both handover priorities or redirection priorities, the third priority is a priority of the cell in the HPLMN of the terminal device, and the fourth priority is a priority of the cell in the current access PLMN of the terminal device.

In a fourth aspect, the present application provides a communication device, which may be a terminal device in any one of the possible designs of the second aspect or the second aspect, or a chip for implementing the functions of the terminal device; the communication device comprises corresponding modules, units or means (means) for realizing the method, and the modules, units or means can be realized by hardware, software or realized by executing corresponding software by hardware. The hardware or software includes one or more modules or units corresponding to the functions described above.

The communication device includes a processing unit, a transmitting unit, and a receiving unit. The receiving unit is configured to receive first information from an access network device of a first public land mobile network PLMN, where the first PLMN is a PLMN currently accessed by the communication device, the first information is used by the communication device to determine to search for a second PLMN, and the first PLMN is different from the second PLMN. And the processing unit is used for searching and residing in the second PLMN according to the first information.

In one possible design, the first PLMN comprises an HPLMN of the communication device and the second PLMN comprises an equivalent public land mobile network EPLMN of the communication device.

In one possible design, the receiving unit is configured to receive second information from a core network device of the first PLMN, where the second information includes area information covered by the second PLMN. A processing unit, configured to search for and reside in a second PLMN according to the first information, including: and determining that the communication device is in the area indicated by the second information according to the area where the access network equipment is located and the second information, and searching and residing in the second PLMN when the communication device is in the area indicated by the second information. Wherein the first information comprises information of a location area where the access network device is located.

In one possible design, the area in the second information includes at least one of: an overlap region, a boundary region, or a first region. Wherein the overlapping area is an area where a service area of the core network device overlaps with a coverage area of the second PLMN, the boundary area is an area where a distance between the overlapping area and a boundary of the overlapping area is smaller than a first threshold, and the first area is an area where a distance between the boundary area and the communication apparatus is smaller than a second threshold.

In one possible design, the second information is transmitted by the terminal device via an attach accept message or a tracking area update TAU accept message.

In one possible design, the second information is transmitted via a user equipment configuration update message.

In one possible design, the first PLMN comprises an EPLMN of the communication device and the second PLMN comprises an HPLMN of the communication device.

In one possible design, the receiving unit is configured to receive second information from a core network device of the first PLMN, where the second information indicates at least a partial coverage area of the first PLMN, and the partial coverage area of the first PLMN belongs to a border area of the first PLMN. A processing unit, configured to search for and reside in a second PLMN according to the first information, including: and determining that the communication device is in the area indicated by the second information according to the area where the access network equipment is located and the second information, and searching and residing in the second PLMN when the communication device is in the area indicated by the second information. Wherein the first information comprises information of a location area where the access network device is located.

In one possible design, the partial coverage area of the first PLMN includes at least one of: an overlap region, or a first region. Wherein the overlapping area is an area where a service area of the core network device overlaps with a border area of the first PLMN, and the first area is an area where a distance between the overlapping area and the communication device is smaller than a second threshold.

In one possible design, the second information is transmitted via a registration accept message.

In one possible design, the processing unit, configured to search for and reside in the second PLMN based on the first information, includes: searching and residing in the second PLMN according to the second PLMN information, wherein the first information comprises the second PLMN information.

In one possible design, the receiving unit is configured to receive the first information from the access network device via a system message.

The first SIB is an SIB for carrying common frequency information, the common frequency information includes frequency point information in the second PLMN, and a frequency point in the common frequency information is the same as a frequency point of a cell where the communication device currently resides. The first SIB may be SIB3 specified in the 3GPP related technical specification, for example.

The second SIB is an SIB for carrying inter-frequency information, the inter-frequency information includes frequency point information in a second PLMN, and a frequency point in the inter-frequency information is different from a frequency point of a cell where the communication device currently resides. The second SIB may be SIB4 specified in the 3GPP related technical specification, for example.

The third SIB is an SIB for carrying inter-system information, where the inter-system information includes information of a communication system of the second PLMN, and the communication system of the inter-system information is different from a communication system of a cell in which the communication device currently resides. The third SIB may be SIB5 specified in the 3GPP related technical specification, for example.

In a fifth aspect, embodiments of the present application provide a communication apparatus, including: a processor and a memory; the memory is configured to store computer instructions that, when executed by the processor, cause the communication apparatus to perform a method performed by the first access network device in any one of the above aspects or any one of the possible designs of any one of the aspects. The communication means may be the first access network device of the first aspect or any of the possible designs of the first aspect, or a chip implementing the functionality of the first access network device.

In a sixth aspect, embodiments of the present application provide a communication apparatus, including: a processor; the processor is coupled to the memory for reading the instructions in the memory and executing the instructions to cause the communication apparatus to perform the method performed by the first access network device in any one of the above aspects or any one of the possible designs of any one of the aspects. The communication means may be the first access network device of the first aspect or any of the possible designs of the first aspect, or a chip implementing the functionality of the first access network device.

In a seventh aspect, embodiments of the present application provide a chip including a processing circuit and an input-output interface. Wherein the input-output interface is for communication with a module outside the chip, which may be, for example, a chip implementing the functionality of the first access network device in the first aspect or any of the possible designs of the first aspect. The processing circuitry is arranged to run a computer program or instructions to implement the method of the first aspect above or any of the possible designs of the first aspect.

In an eighth aspect, embodiments of the present application provide a communication apparatus, including: a processor and a memory; the memory is for storing computer instructions which, when executed by the processor, cause the communications apparatus to perform the method performed by the terminal device in any one of the above aspects or any one of the possible designs of any one of the aspects. The communication means may be a terminal device in the second aspect or any of the possible designs of the second aspect, or a chip implementing the functions of the terminal device.

In a ninth aspect, embodiments of the present application provide a communication apparatus, including: a processor; the processor is coupled to the memory for reading the instructions in the memory and executing the instructions to cause the communication device to perform the method performed by the terminal device as in any one of the above aspects or any one of the possible designs of the aspect. The communication means may be a terminal device in the second aspect or any of the possible designs of the second aspect, or a chip implementing the functions of the terminal device.

In a tenth aspect, embodiments of the present application provide a chip including a processing circuit and an input-output interface. Wherein the input-output interface is for communication with a module outside the chip, which may be, for example, a chip implementing the functionality of the terminal device in the second aspect or any of the possible designs of the second aspect. The processing circuitry is configured to run a computer program or instructions to implement the method of the second aspect above or any of the possible designs of the second aspect.

In an eleventh aspect, embodiments of the present application provide a computer-readable storage medium having instructions stored therein that, when run on a computer, cause the computer to perform the method of any one of the above aspects.

In a twelfth aspect, embodiments of the present application provide a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any one of the above aspects.

In a thirteenth aspect, embodiments of the present application provide circuitry comprising processing circuitry configured to perform the method of any one of the above aspects.

The technical effects of any one of the designs of the third aspect to the thirteenth aspect may refer to the advantages of the corresponding methods provided above, and are not described herein.

Drawings

Fig. 1 is a schematic architecture diagram of a communication system according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a communication system according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a communication system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a communication system according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a communication system according to an embodiment of the present application;

fig. 6a is a schematic diagram of a network coverage scenario provided in an embodiment of the present application;

fig. 6b is a schematic diagram of still another network coverage scenario provided in an embodiment of the present application;

fig. 6c is a schematic diagram of still another network coverage scenario provided in an embodiment of the present application;

fig. 7 is a schematic flow chart of a communication method according to an embodiment of the present application;

fig. 8 is a flow chart of still another communication method according to an embodiment of the present application;

fig. 9 is a flow chart of another communication method according to an embodiment of the present application;

fig. 10 is a flow chart of another communication method according to an embodiment of the present application;

FIG. 11a is a flowchart illustrating another communication method according to an embodiment of the present disclosure;

FIG. 11b is a flowchart illustrating another communication method according to an embodiment of the present disclosure;

Fig. 12 is a flow chart of another communication method according to an embodiment of the present application;

fig. 13 is a flow chart of another communication method according to an embodiment of the present application;

fig. 14a is a flow chart of another communication method according to an embodiment of the present application;

fig. 14b is a flowchart of another communication method according to an embodiment of the present application;

fig. 14c is a flowchart of another communication method according to an embodiment of the present application;

fig. 14d is a flow chart of another communication method according to an embodiment of the present application;

fig. 14e is a schematic diagram of still another network coverage scenario provided in an embodiment of the present application;

fig. 15 is a flow chart of another communication method according to an embodiment of the present application;

fig. 16 is a schematic diagram of still another network coverage scenario provided in an embodiment of the present application;

fig. 17 is a flow chart of another communication method according to an embodiment of the present application;

fig. 18 is a flow chart of another communication method according to an embodiment of the present application;

fig. 19 is a flow chart of yet another communication method according to an embodiment of the present application;

FIG. 20 is a layered schematic diagram of a communication protocol according to an embodiment of the present application;

fig. 21 is a flow chart of another communication method according to an embodiment of the present application;

Fig. 22 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 23 is a schematic structural diagram of still another communication device according to an embodiment of the present application.

Detailed Description

Fig. 1 is a schematic architecture diagram of a communication system according to an embodiment of the present application. As shown in fig. 1, the communication system includes a terminal device, an access network device, and a core network.

The terminal device comprises a device for providing voice and/or data connectivity to a user, specifically, a device for providing voice to a user, a device for providing data connectivity to a user, or a device for providing voice and data connectivity to a user. For example, may include a handheld device having wireless connectivity, or a processing device connected to a wireless modem. The terminal device may communicate with the core network via a radio access network (radio access network, RAN), exchange voice or data with the RAN, or interact voice and data with the RAN. The terminal device may include a User Equipment (UE), a wireless terminal device, a mobile terminal device, a device-to-device (D2D) terminal device, a vehicle-to-device (V2X) terminal device, a machine-to-machine/machine-type communication (M2M/MTC) terminal device, an internet of things (internet of things, ioT) terminal device, a subscription unit (subscriber unit), a subscription station (subscriber station), a mobile station (mobile station), a remote station, an Access Point (AP), a remote terminal (remote terminal), an access terminal (access terminal), a user terminal (user terminal), a user agent (user agent), or a user equipment (user device), etc. For example, mobile telephones (or "cellular" telephones) computers with mobile terminal devices, portable, pocket, hand-held, computer-built mobile devices, and the like may be included. Such as personal communication services (personal communication service, PCS) phones, cordless phones, session initiation protocol (session initiation protocol, SIP) phones, wireless local loop (wireless local loop, WLL) stations, personal digital assistants (personal digital assistant, PDAs), and the like. But also limited devices such as devices with lower power consumption, or devices with limited memory capabilities, or devices with limited computing capabilities, etc. Examples include bar codes, radio frequency identification (radio frequency identification, RFID), sensors, global positioning systems (global positioning system, GPS), laser scanners, and other information sensing devices.

While the various terminal devices described above, if located on a vehicle (e.g., placed in a vehicle or mounted in a vehicle), may be considered as in-vehicle terminal devices, for example, also referred to as in-vehicle units (OBUs).

In the embodiment of the application, the terminal device may further include a relay (relay). Or it is understood that all that is capable of data communication with a base station can be seen as a terminal device.

In the embodiment of the present application, the device for implementing the function of the terminal device may be the terminal device, or may be a device capable of supporting the terminal device to implement the function, for example, a chip system, and the device may be installed in the terminal device. In the embodiment of the application, the chip system may be formed by a chip, and may also include a chip and other discrete devices. In the technical solution provided in the embodiment of the present application, an apparatus for implementing a function of a terminal is taken as an example of a terminal device, and description is made.

The access network device may be an access point for wireless communication or wired communication, such as a base station or a base station controller, a wireless-fidelity (wifi) access point or a wifi controller, or a fixed network access point, etc. The base stations may include various types of base stations, for example: micro base stations (also referred to as small stations), macro base stations, relay stations, access points, etc., as embodiments of the present application are not specifically limited. In the embodiment of the present application, the base station may be a base station (base transceiver station, BTS) in a global system for mobile communications (global system for mobile communication, GSM), a base station (base transceiver station, BTS) in a code division multiple access (code division multiple access, CDMA), a base station (node B) in a wideband code division multiple access (wideband code division multiple access, WCDMA), an evolved base station (evolutional node B, eNB or e-NodeB) in a long term evolution (long term evolution, LTE), an eNB in the internet of things (internet of things, ioT) or a narrowband internet of things (narrow band-internet of things, NB-IoT), a base station in a fifth generation (the fifth generation, 5G) mobile communication network or a public land mobile network (public land mobile network, PLMN) of future evolution, which is not limited in any way by the embodiments of the present application.

The core network includes various core network devices, such as an access management network element, a session management network element, and the like. The access management network element is mainly used for mobility management, access management and the like, and can be used for realizing other functions besides session management, such as legal interception, access authorization/authentication and the like, in the functions of the mobility management entity (mobility management entity, MME). In a 5G communication system, the access management network element may comprise an access and mobility management function (core access and mobility management function, AMF) network element. The session management network element is mainly used for session management, network interconnection protocol (internet protocol, IP) address allocation and management of terminal equipment, terminal node for selecting manageable user plane functions, policy control and charging function interfaces, downlink data notification and the like. In a fifth generation (the fifth generation, 5G) communication system, the session management network element may comprise a session management function (session management function, SMF) network element. The MME may refer to the description of fig. 2, and the AMF network element and the SMF network element may refer to the description of fig. 3. It should be understood that the core network device may also include other network elements, such as a user plane function (user plane function, UPF) network element, a session management function (session management function, SMF) network element, etc., which are not described herein.

By way of example, fig. 2 shows a schematic architecture of a fourth generation (the fourth generation, 4G) communication system. The 4G communication system includes network elements or devices such as evolved universal mobile telecommunications system (universal mobile telecommunications system, UMTS) terrestrial radio access network (evolved UMTS territorial radio access network, E-UTRAN) devices, MME, serving Gateway (SGW), packet data network (packet data network, PDN) Gateway (PGW), policy and charging rules function (policy and charging rules function, PCRF) network elements, and home subscriber server (home subscriber server, HSS).

The terminal equipment accesses the E-UTRAN equipment through LTE-Uu, the E-UTRAN equipment communicates with MME through S1-MME, the E-UTRAN equipment communicates with SGW through S1-U, different MME communicates with HSS through S10 (only one MME is shown in an exemplary way in fig. 2), MME communicates with HSS through S6a, MME communicates with SGW through S11, PGW communicates with PCRF network element through Gx, PCRF network element communicates with server through Rx, SGW communicates with PGW through S5, and PGW accesses server through SGi.

Wherein the E-UTRAN equipment is used for realizing the functions related to the evolution network wireless. The MME is responsible for mobility management of a control plane, including user context and mobility state management, allocation of user temporary identity, and the like. SGW is a third generation partnership project (3rd generation partnership project,3GPP) inter-access network user plane anchor and is an interface to terminate E-TURAN. PGW is a user plane anchor point between 3GPP access network and non-3 GPP access network, and is an interface for termination and external PDN. The PCRF network element is used for policy control decision and flow charging control functions. The HSS is used to store subscriber subscription information. The server is used to provide internet protocol (internet protocol, IP) services such as voice/video services based on internet protocol multimedia subsystem (internet protocol multimediasubsystem, IMS), packet switched streaming services (packet switched streaming service, PSS), etc.

By way of example, fig. 3 shows a schematic architecture of a 5G communication system. The 5G communication system includes a radio access network (radio access network, RAN) device, a user plane function (user plane function, UPF) network element, an AMF network element, an SMF network element, an authentication server function (authentication server function, AUSF) network element, a network slice selection function (network slice selection function, NSSF) network element, a network opening function (network exposure function, NEF) network element, a network function storage function (network exposure function repository function, NRF) network element, a policy control function (policy control function, PCF) network element, a unified data management (unified data management, UDM) network element, a unified data storage (unified data repository, UDR) network element, an application function (application function, AF) network element, or a billing function (charging function, CHF) network element, etc.

It should be noted that fig. 3 is only an example given as to some network elements or entities in the 5G communication system, and the 5G communication system may further include some network elements or entities not shown in fig. 3, such as network data analysis function (network data analytics function, NWDAF) network elements, which are not specifically limited in this embodiment of the present application.

As shown in fig. 3, the terminal device accesses the 5G network through the RAN device, and the terminal device communicates with the AMF through an N1 interface (abbreviated as N1); the RAN equipment communicates with an AMF network element through an N2 interface (N2 for short); the RAN equipment communicates with UPF network elements through an N3 interface (N3 for short); the SMF network element communicates with the UPF network element through an N4 interface (abbreviated as N4), and the UPF network element accesses a Data Network (DN) through an N6 interface (abbreviated as N6). In the architecture shown in fig. 3, N1, N2, N3, N4 and N6 represent reference points (reference points) between related network elements/network functions, respectively.

In addition, control plane functions such as an AUSF network element, an AMF network element, an SMF network element, an NSSF network element, a NEF network element, an NRF network element, a PCF network element, a UDM network element, a UDR network element, a CHF network element, or an AF network element shown in fig. 3 use a service interface to perform interaction. For example, the server interface provided by the AUSF network element is Nausf; the AMF network element provides a service interface as Namf; the SMF network element provides a serving interface as Nsmf; the NSSF network element provides a service interface for the outside as Nnssf; the network element of NEF provides a service interface for the outside as Nnef; the service interface externally provided by the NRF network element is Nnrf; the service interface externally provided by the PCF network element is an Npcf; the service interface externally provided by the UDM network element is Nudm; the server interface externally provided by the UDR network element is Nudr; the service interface externally provided by the CHF network element is Nchf; the service interface provided by the AF network element is Naf. The related functional descriptions and interface descriptions may refer to the 5G system architecture (5G system architecture) in the 23501 standard, and are not described herein.

It should be understood that the names of the above-mentioned core network devices, such as MME, SMF, AMF, etc., are only one name, and the device itself is not limited. It will be appreciated that other names may be used in 5G networks and other networks in the future, and embodiments of the present application are not specifically limited thereto. For example, the AMF network element may also be referred to as an AMF or an AMF entity, which is generally described herein, and will not be described in detail herein.

Alternatively, the core network device may be implemented by one device, or may be implemented by a plurality of devices together, or may be a functional module in one device, which is not specifically limited in this embodiment of the present application. It will be appreciated that the functional modules described above may be either network elements in a hardware device, software functional modules running on dedicated hardware, or virtualized functional modules instantiated on a platform (e.g., a cloud platform).

In order to facilitate understanding of the embodiments of the present application, the following description will be given for the terms involved in the embodiments of the present application. It should be understood that these descriptions are merely for the purpose of facilitating understanding of the embodiments of the present application and should not be construed as limiting the application in any way.

1. Communication system

Communication formats, including but not limited to: second generation mobile communication technology (2 nd-generation wireless telephone technology, 2G) networks, third generation mobile communication technology (3 rd-generation wireless telephone technology, 3G) networks, fourth generation mobile communication technology (4 th-Generation wirelesstelephone technology, 4G) networks, fifth generation mobile communication technology (5 th-Generation wirelesstelephone technology, 5G) networks, and so forth. Such as global system for mobile communications (global system of mobilecommunication, GSM) networks, code division multiple access (code division multiple access, CDMA) networks, wideband code division multiple access (wideband code division multiple access, WCDMA) networks, universal mobile telecommunications system (universal mobile telecommunications system, UMTS), long term evolution (long termevolution, LTE) networks, and the like.

2、PLMN

A PLMN is a network established and operated by a government or its approved operators to provide land mobile services to the public. The PLMNs are interconnected with the public switched telephone network to form a communication network on a regional or national scale.

The PLMN consists of a mobile country number (mobile contrary code, MCC) and a mobile network number (MNC). MCC uniquely indicates the country to which the mobile subscriber belongs. For example, chinese MCC is 460. MNCs may uniquely represent networks in that country. For example, the MNC corresponding to chinese movement may include 00 and the MNC corresponding to chinese communication includes 01. Wherein different network operators may correspond to different PLMNs. For example, a chinese mobile PLMN may include 46000, 46002, 46004, 46007, 46008; the PLMN of chinese communication may include 46001, 46006, 46009 and 46010. PLMNs of chinese telecommunications may include 46003, 46011 and 46012; the PLMN of china radio may include 46015. The PLMNs corresponding to the network operators may further include other PLMNs, which are not limited in this embodiment of the present application.

It is often necessary for a terminal device to maintain at least one type of PLMN. The types of PLMNs are described as follows:

the home public land mobile network (home PLMN, HPLMN) refers to a PLMN in the global subscriber identity card (universal subscriber identity module, USIM) of the terminal equipment corresponding to the international mobile subscriber identity (international mobile subscriber identity, IMSI). For a certain terminal device, the number of HPLMNs of the terminal device is one. Taking the china mobile operator as an example, the HPLMN comprises 46000 identified PLMNs for terminal devices of which the home network operator is china mobile. Taking the chinese group operator as an example, the HPLMN includes a PLMN identified by 46001 for terminal equipment of the chinese group by the home network operator. The HPLMN may also be described as a home network, and in the embodiment of the present application, both refer to the same meaning and may be interchanged.

A Visited Public Land Mobile Network (VPLMN) refers to a PLMN that the terminal equipment is visiting. For a certain terminal device, the VPLMN is different from the HPLMN of the terminal device. The MCC, MNC in VPLMN and IMSI are not exactly the same. The VPLMN may also be described as a visited network, and in this embodiment of the present application, both refer to the same meaning and may be interchanged.

An Equivalent Public Land Mobile Network (EPLMN) refers to a PLMN that is located in the same place as the HPLMN of the terminal equipment and has the same priority as the HPLMN. For a certain terminal device, the number of EPLMNs of that terminal device is one or more. As a possible scenario, the network to which the EPLMN corresponds is typically referred to as other PLMNs belonging to the network operator. Illustratively, for example, the home network operator is a terminal device of China mobile, the EPLMN may include a PLMN identified as 46002, 46004, 46007, or 46008. Taking the chinese group operator as an example, the EPLMN may include a PLMN identified by 46006, 46009 or 46010 for terminal equipment of the chinese group by the home network operator.

As another possibility, the EPLMN corresponding network may also comprise PLMNs of other network operators than the home network operator. It is understood that PLMNs that are shared by other network operators, i.e. PLMNs that other network operators allow the terminal device to access. Illustratively, taking the example of a China mobile operator, china mobile provides a PLMN for shared services to China Unicom, such as the EPLMN identified by 46030. China mobile provides a PLMN of shared services to china telecommunications, such as EPLMN identified by 46031. In the embodiment of the present application, only the shared EPLMN is used as an example for description.

For the terminal device, if the terminal device is in the home location, the terminal device selects the HPLMN as the accessed PLMN, or the EPLMN of the home network operator as the accessed PLMN. If the terminal device is within the coverage area of the shared EPLMN, the terminal device may select an EPLMN access shared by other network operators, which selected EPLMN may be described as a VPLMN.

3. Heterogeneous network roaming

Foreign network roaming means that the terminal equipment obtains network services in the home network country by accessing other network operators PLMN. For example, a user of a terminal device in chinese communication accesses a chinese mobile network in china to obtain a network service. After the terminal equipment accesses the visiting network, the service provided by the home network can be used, and the service provided by the access network can also be used. The access network and the core network of the different network roaming operators are independently constructed and managed, and the mobile users are independently managed. The two operators providing the different network roaming service provide corresponding services for the roaming terminal equipment based on the inter-network roaming agreement. The heterogeneous network roaming can be realized by adopting a home routing mode, namely roaming user data returns to a home network, and the service is provided by the home network to terminal equipment, or the service provided by an access network can be directly used.

For heterogeneous roaming, the core network device of the home network sends the PLMN information of the shared visited network, such as PLMN ID, to the terminal device in the form of EPLMN information. When the terminal equipment is in the coverage area of the visiting network, the terminal equipment can access to the EPLMN based on the EPLMN information.

Illustratively, in a 5G independent networking (SA) scenario, the terminal device is within an area where the terminal device cannot access the HPLMN to obtain 5G services, such as 5G data traffic, IMS-based voice/video traffic VONR, short message traffic, etc., due to the area not having coverage of the HPLMN network (e.g., no network including 2G/3G/4G/5G coverage), or only having coverage of the HPLMN network of a low communication system (e.g., only 2G/3G/4G coverage, no 5G coverage; or only 2G/3G coverage, no 4G/5G coverage). In this case, the heterogeneous network roaming may also be described as 5G core network heterogeneous network roaming or 5G core network roaming. In the embodiment of the present application, only 5G core network foreign network roaming is taken as an example for description.

Referring to fig. 4, fig. 4 shows a network architecture diagram of 5G core network foreign network roaming. The visited network and the home network are connected by a Border Gateway (BG). The 5G core network different network roaming support provides roaming service for a plurality of network operators, and terminal equipment of different network operators can be connected to the 5G core network to which each belongs through 5G network access of a visited network. In fig. 4, only two home networks are taken as an example for description. Specifically, the terminal device of the home network 1 is connected to the 5G core network of the home network 1 through the 5G network access of the visited network. The terminal equipment of the home network 2 is connected to the 5G core network of the home network 2 through the 5G network access of the visited network.

Referring to fig. 5, fig. 5 shows a network architecture diagram of still another 5G core network foreign network roaming. The PLMN as the visited network is denoted VPLMN. The SMF network elements in the VPLMN are called visited-SMF (V-SMF) network elements. The AMF network element in the VPLMN is called a visited-AMF (V-AMF) network element. The PLMN as the home network is denoted HPLMN. The SMF network element in the HPLMN is called home-SMF (H-SMF) network element. The PCF network element in the HPLMN is called a home PCF (H-PCF) network element.

4. Shared network, shared area

A shared network refers to a network that allows or is dedicated to terminal equipment access of other network operators (other network operators than the home network operator). Illustratively, taking the example of a China mobile operator, china mobile provides a PLMN for shared services to China Unicom, such as the EPLMN identified by 46030. 46030 the EPLMN identified may be a PLMN dedicated to providing shared services to chinese trunks. China mobile provides a PLMN of shared services to china telecommunications, such as EPLMN identified by 46031. 46031 the EPLMN identified may be a PLMN dedicated to providing shared services to chinese telecommunications.

The coverage area of the shared network may be described as a shared area. The shared network may be a 5G network or a network of other communication systems, and the embodiment of the present application is described by taking a 5G network as an example. Accordingly, the area covered by the shared 5G network may be described as a shared 5G area, as shown by the diagonally filled area in fig. 6a (or fig. 6b, or fig. 6 c).

For example, in the case of a china mobile operator, the china mobile provides the other network operators with the identity of the shared 5G network, the MCC has a value of 460 and the mnc has a value of 30.

5. Non-shared network, non-shared area

The non-shared network refers to a network to which terminal devices of other network operators are not allowed to access, except for terminal devices of their own home network operators. The coverage area of the non-shared network may be described as a non-shared area. The non-shared network may be a 5G network, or may be a network of other communication systems, and the embodiment of the present application is described only by taking the 5G network as an example. Accordingly, the area covered by the unshared 5G network may be described as an unshared 5G area, as shown by the area without diagonal filling in fig. 6a (or fig. 6b, or fig. 6 c).

For example, still taking the operator china mobile as an example, in the identity of the non-shared 5G network that china mobile gives itself to use, the MCC has a value of 460 and the mnc has a value of 00, or the MCC has a value of 460 and the mnc has a value of 02.

It should be noted that, if the terminal device is in the non-shared area, the terminal device needs to access its home network.

Illustratively, taking fig. 6a as an example, the area identified by the non-diagonal and gridline filled portions refers to the same area being covered by both the visited network and the non-shared 5G network, and by the home network 4G network and/or the home network 5G network. In this case, the terminal device in the area accesses the home network. The area identified by the diagonally filled portion means that the same area is covered by both the visited network sharing 5G network and the home network 4G network. In this case, the terminal device in the area can access the visited network to achieve better data transmission performance. The area identified by the grid line filled part refers to that the same area is covered by the visited network sharing 5G network and the visited network non-sharing 5G network. In this case, if the terminal device moves from the diagonally filled area to the blank area, the terminal device needs to be switched, redirected or reselected from the visited network to the home network to perform the service transmission normally. Otherwise, if the terminal device moves from the blank area to the area filled with oblique lines, the terminal device needs to be switched, redirected or reselected from the home network to the visiting network so as to normally perform service transmission.

Note that in fig. 6a, the area indicated by 601a indicates the coverage area of the visited network that is not the shared 5G network. The area indicated by 602a represents the area covered by both the visited network and the non-shared 5G network as well as the visited network shared 5G network. The area indicated by 603a represents the area covered by the visited network shared 5G network. The area indicated by 601b represents the coverage area of the home network 5G network and/or the home network 4G network. The area indicated by 602b represents the area covered by both the home network 5G network and the home network 4G network. 603b, the area covered by the home network 4G network. In terms of actual geographic locations, 601a and 601b refer to the same area, 602a and 602b refer to the same area, and 603a and 603b refer to the same area. The blank elliptical areas in fig. 6b (or fig. 6 c) may be referred to the description of 601a and 601b, and the diagonally filled elliptical areas in fig. 6b (or fig. 6 c) may be referred to the description of 603a and 601 b.

Illustratively, taking fig. 6b or fig. 6c as an example, the area identified by the oval area filled with no oblique lines refers to the area covered by the visited network and the non-shared 5G network. The area identified by the oval area filled with oblique lines refers to the area covered by the visited network sharing 5G network. In fig. 6b, the non-shared 5G network coverage area is tangential to the shared 5G network coverage area. In fig. 6b, the coverage area of the non-shared 5G network is neither overlapped nor tangential to the coverage area of the shared 5G network, and the coverage areas are adjacent to each other, for example, the separation distance between the coverage area of the non-shared 5G network and the coverage area of the shared 5G network is smaller than a certain preset value. In fig. 6b or fig. 6c, if the terminal device moves from the diagonally filled area to the blank area, the terminal device needs to switch, redirect or reselect from the visited network-shared 5G network to the home network for normal traffic transmission. Otherwise, if the terminal equipment moves from the blank area to the area filled with oblique lines, the terminal equipment needs to be switched, redirected or reselected from the home network to the visiting network sharing 5G network so as to normally perform service transmission.

6. Radio resource control (radio resource control, RRC) state

In a 4G network, two RRC states are supported, namely an RRC IDLE state (rrc_idle), an RRC CONNECTED state (rrc_connected). In a 5G network, three RRC states are supported, namely, RRC IDLE state (rrc_idle), RRC INACTIVE state (rrc_inactive), RRC CONNECTED state (rrc_connected). Wherein the different RRC states can be switched.

And when the terminal equipment is in the RRC connection state, the terminal equipment receives measurement configuration information from the access network equipment. The measurement configuration information includes information of a frequency point, or includes information of the frequency point and information of a cell corresponding to the frequency point, such as physical-layer cell identity (PCI). The frequency point in the measurement configuration information belongs to the frequency point in the PLMN to which the terminal equipment is currently accessed. The terminal device measures the frequency points in the measurement configuration information to obtain a measurement report (measurement report). The terminal equipment sends a measurement report to the access network equipment, and correspondingly, the access network equipment receives the measurement report from the terminal equipment. The access network device then decides on the target cell based on the measurement report to cause the terminal device to perform a cell handover (handover) or redirection (redirection).

The cell handover refers to that the terminal device moves from one cell to another cell geographically, and the two cells may be the same communication system cell, such as a 5G cell. The redirection means that the terminal equipment in the connection state releases the connection first and then re-accesses the target cell. For the terminal device, the communication system of the cell before redirection and the cell after redirection can be the same or different.

And when the terminal equipment is in the RRC idle state, receiving the system message from the access network equipment. The system information comprises same-frequency information, different-frequency information and different-system information. The common-frequency information comprises frequency point information in a PLMN (public land Mobile network) which is accessed by the terminal equipment at present, the frequency point is the same as the frequency point of a cell in which the terminal equipment is currently resident, the different-frequency information comprises frequency point information in the PLMN which is accessed by the terminal equipment at present, the frequency point is different from the frequency point of the cell in which the terminal equipment is currently resident, and the different-system information comprises information of a communication system of the PLMN which is accessed by the terminal equipment at present, wherein the communication system is different from the communication system of the cell in which the terminal equipment is currently resident. The terminal device in the idle state performs measurement based on the above information (like frequency information, inter-frequency information, and inter-system information) to obtain a measurement result. And then, the terminal equipment performs cell reselection according to the measurement result.

However, in some scenarios, the measurement configuration information and the system message do not configure measurement information of a different network (other PLMNs than the PLMN to which the terminal device accesses), so the terminal device cannot switch, redirect or reselect between the visited network and the home network, resulting in a failure of normal transmission of the service and poor user experience.

In view of this, the embodiments of the present application provide two communication methods, and the communication method (such as the first communication method or the second communication method) of the embodiments of the present application may be applied to the communication system shown in fig. 1. In the embodiment of the present application, for a network element in the VPLMN of the terminal device, for example, the access network device may be described as a first access network device, and the core network device may be described as a first core network device. For network elements in the HPLMN of the terminal device, such as the access network device may be described as a third access network device, the core network device may be described as a third core network device. For simplicity of description, the HPLMN of the terminal device may also be simply referred to as HPLMN. The EPLMN of the terminal device may also be simply referred to as EPLMN, and the VPLMN of the terminal device may also be simply referred to as VPLMN. The names of messages between network elements or the names of parameters in the messages in the embodiments described below are only examples, and other names may be used in specific implementations. This is generally described herein, and will not be described in detail.

Example 1

A first embodiment will be described with reference to fig. 7 to 11. An embodiment one may be a first communication method provided in the embodiments of the present application.

In the first communication method provided by the embodiment of the present application, a first access network device obtains HPLMN information of a terminal device, where the first access network device is an access network device in a PLMN to which the terminal device is currently connected, and the PLMN to which the terminal device is currently connected is different from the HPLMN of the terminal device. Then, the first access network device sends first information to the terminal device according to the HPLMN information of the terminal device, wherein the first information relates to the HPLMN of the terminal device, and the first information is used for measurement, HPLMN searching or reselection by the terminal device. In this way, when the terminal device performs measurement based on the first information, heterogeneous network measurement can be performed, which lays a foundation for the terminal device to switch or redirect from the currently accessed PLMN to the HPLMN. When the terminal equipment searches the HPLMN based on the first information, the frequency points in the HPLMN can be searched, a measurement report of the different network is generated, and the base is laid by switching or redirecting to the HPLMN. When the terminal equipment reselects based on the first information, the terminal equipment can reselect the HPLMN to normally perform service transmission because the first information is related to the HLMN, thereby being beneficial to improving user experience.

As shown in fig. 7, a first communication method 700 provided in an embodiment of the present application includes the following steps:

s701, the first access network equipment acquires HPLMN information of the terminal equipment.

The first access network device is an access network device in the PLMN to which the terminal device is currently connected. The PLMN to which the terminal equipment is currently connected is different from the HPLMN of the terminal equipment. That is, the terminal device is currently accessing the VPLMN and not accessing the HPLMN, as shown in fig. 5.

Wherein the HPLMN information of the terminal device indicates the HPLMN of the terminal device. Illustratively, the HPLMN information may be an HPLMN ID. It should be understood that the HPLMN information may be implemented as other forms of information to indicate the HPLMN of the terminal device, and the embodiment of the present application is only exemplarily described with the HPLMN ID.

Optionally, the implementation procedure of S701 includes the following three modes (mode 1 to mode 3 below):

as shown in the block of "mode 1" in fig. 8, S701 may be implemented as S701a:

s701a, the first core network device sends HPLMN information of the terminal device to the first access network device. Correspondingly, the first access network device receives HPLMN information from the terminal device of the first core network device.

The first core network device is a core network device in a PLMN to which the terminal device is currently connected. Taking the initial registration procedure of the terminal device as an example, the first core network device is a core network device that receives a registration request (registration accept) sent by the terminal and provides a registration accept (registration accept) message for the terminal device. Illustratively, taking a 5G network as an example, the first core network device may be implemented as an AMF network element. The following is a description of the process shown in fig. 9:

Taking the registration procedure of the terminal device in the VPLMN as an example, referring to fig. 9, fig. 9 shows a method flowchart of a possible registration procedure, specifically the steps are as follows:

s11, the terminal equipment sends an RRC establishment request (RRC Setup Request) message to the first access network equipment. Correspondingly, the first access network device receives the RRC establishment request message from the terminal device.

The RRC connection establishment request message is used to request establishment of an RRC connection. Illustratively, the RRC setup request message includes at least one of: identification of the terminal equipment and establishment cause. The identity of the terminal device may include, among other things, a temporary mobile subscription identifier (5G S-temporary mobile subscriber identity, 5G-S-TMSI). The establishment cause includes, but is not limited to, at least one of: calling signaling, calling data, calling voice telephone, calling video telephone, calling text message, emergency call, etc.

S12, the first access network equipment sends an RRC Setup message to the terminal equipment. Correspondingly, the terminal device receives the RRC setup message from the first access network device.

The RRC setup message is used to establish configuration of the radio signaling bearer.

S13, the terminal equipment sends an RRC establishment completion (RRC Setup Complete) message to the first access network equipment. Correspondingly, the first access network device receives the RRC setup complete message from the terminal device.

The RRC setup complete message includes a registration request (registration request) message and information of the PLMN to which the terminal device selects to access, such as a PLMN ID.

S14, the first access network equipment sends a registration request message to the first core network equipment. Correspondingly, the first core network device receives a registration request message from the first access network device.

For the first core network device, the first core network device performs S15 and S16 when the first core network device cannot determine the identity of the terminal device, such as subscription hidden identifier (subscription concealed identifier, sui). Otherwise, when the first core network device is able to determine the identity of the terminal device, the first core network device performs S17. The descriptions of S15, S16, and S17 are as follows:

s15, the first core network device sends an Identity request (Identity request) message to the terminal device. Correspondingly, the terminal device receives the identification request message from the first core network device.

The identification request message is used for requesting the identification of the terminal equipment.

S16, the terminal equipment sends an identification response (Identity response) message to the first core network equipment. Correspondingly, the first core network device receives the identification response message from the terminal device.

Wherein the identity response message comprises an identity of the terminal device, such as a sui.

S17, when the first core network device determines that the terminal device is in a roaming state, the first core network device sends an initial context establishment request (Initia Context Setup Request) message to the first access network device. Accordingly, the first access network device receives an initial context setup request message from the first core network device.

Wherein the initial context setup request message includes HPLMN information of the terminal device and a registration accept (Registration accept) message.

S18, the first access network equipment sends a registration acceptance message to the terminal equipment. Correspondingly, the terminal device receives a registration acceptance message from the first access network device.

Since the initial context setup request message of S17 includes HPLMN information of the terminal device, the first access network device may acquire the HPLMN information of the terminal device through a registration procedure, so that the first access network device determines whether to execute the differentiated mobility management policy.

As shown in the block of "mode 2" in fig. 8, S701 may be implemented as S701b and S701c:

s701b, the terminal device sends second information to the first access network device. Correspondingly, the first access network device receives the second information from the terminal device.

Wherein the second information includes information of the current access of the terminal device to the PLMN, such as PLMN ID.

For example, china mobile provides shared services to another network operator, such as china corporation. In this case, the first access network device is a china mobile base station, which broadcasts PLMN IDs including 460,30. Wherein 460,30 is EPLMN shared by chinese mobile to chinese UNICOM. For terminal equipment of China Unicom, the terminal equipment selects to access the PLMN identified by 460,30. Accordingly, the second information includes 460,30.

For another example, china mobile provides shared services to two or more other network operators, such as china corporation and china telecommunications. In this case, the first access network device is a china mobile base station, which broadcasts PLMN IDs including 460,30 and 460,31. Wherein 460,30 is EPLMN shared by chinese mobile to chinese UNICOM, 460,31 is EPLMN shared by chinese mobile to chinese telecom. For terminal equipment of China Unicom, the terminal equipment selects to access the PLMN identified by 460,30. Accordingly, the second information includes 460,30. For terminal equipment for home network operator china telecommunications, the terminal equipment selects to access the PLMN identified by 460,31. Accordingly, the second information includes 460,31.

S701c, the first access network equipment determines HPLMN information of the terminal equipment according to the second information and the corresponding relation information.

The description of the corresponding relation information is as follows:

the correspondence information at least includes information of correspondence between a current access PLMN of the terminal device and an HPLMN of the terminal device.

For example, still taking china mobile to provide a shared service to another network operator, such as china communication, the correspondence information may include correspondence information between 460,01 and 460,30. Wherein 460,01 is a PLMN for chinese group to provide services to its mobile subscribers.

For another example, still taking china mobile to provide shared services to two or more other network operators, such as china communication and china telecom, the correspondence information may include correspondence information between 460,01 and 460,30, and correspondence information between 460,03 and 460,31. Wherein 460,01 is a PLMN for china communication providing service to its mobile subscribers, 460,03 is a PLMN for china telecommunication providing service to its mobile subscribers.

For example, for the first access network device, the correspondence information may be preconfigured, or may be information provided by the first core network device to the first access network device, which is not limited in the embodiment of the present application.

Exemplary, the implementation procedure of S701c is as follows:

for example, still taking china mobile to provide a sharing service to another network operator, such as china communication, the first access network device determines that the HPLMN information is 460,01 according to 460,30 (i.e. the second information) and the corresponding relationship information between 460,01 and 460,30 (i.e. the corresponding relationship information described above).

For another example, still taking china mobile to provide a shared service to two or more network operators, such as china communication and china telecom, for a terminal device whose home network operator is china communication, the first access network device determines that HPLMN information is 460,01 according to 460,30 (i.e. the second information) and correspondence information between 460,01 and 460,30 (i.e. the correspondence information mentioned above). For terminal equipment whose home network operator is china telecommunication, the first access network device determines that HPLMN information is 460,03 according to 460,31 (i.e. the second information) and the correspondence information between 460,03 and 460,31 (i.e. the correspondence information described above).

Thus, the first access network device can determine the HPLMN information of the terminal device based on the second information reported by the terminal device.

As shown in the block of "mode 3" in fig. 8, S701 may be implemented as S701d:

s701d, the terminal equipment sends HPLMN information to the first access network equipment. Accordingly, the first access network device receives HPLMN information from the terminal device.

The HPLMN information in S701d is HPLMN information of the terminal device, such as an HPLMN ID.

Illustratively, still taking china mobile as an example for providing shared services to other network operators, in this case the first access network device is a china mobile base station. For terminal devices of chinese group for the home network operator, the HPLMN information sent by the terminal device to the first access network device includes 460,01. For terminal devices whose home network operator is china telecommunications, the HPLMN information sent by the terminal device to the first access network device includes 460,03.

Thus, the first access network device can obtain HPLMN information from the terminal device.

Alternatively, in some embodiments, the second information in S701b (or HPLMN information in S701 d) may be transmitted by:

for example, the second information in S701b (or HPLMN information in S701 d) may be carried in an RRC setup request message through which to transmit. For example, the terminal device transmits the second information (or HPLMN information) to the first access network device through an RRC setup request message. Accordingly, the first access network device receives the second information (or HPLMN information) from the terminal device through the RRC setup request message.

For another example, the second information in S701b (or HPLMN information in S701 d) may be carried in an RRC setup complete message, through which transmission is completed. For example, the terminal device transmits the second information (or HPLMN information) to the first access network device through an RRC setup complete message. Accordingly, the first access network device receives the second information (or HPLMN information) from the terminal device through the RRC setup complete message.

It should be understood that, only the RRC establishment request message and the RRC establishment complete message are taken as examples, the transmission of the second information in S701b (or the HPLMN information in S701 d) is described, and of course, the second information in S701b (or the HPLMN information in S701 d) may also be transmitted through other messages, which is not limited in the embodiment of the present application.

In "mode 3" of fig. 8, the terminal device may also send PLMN information of its own selected access to the first access network device. The PLMN information and the HPLMN information in S701d, which are selectively accessed by the terminal device, may be transmitted through the same message, or may be transmitted through different messages, which is not limited in the embodiment of the present application.

S702, the first access network equipment determines first information according to HPLMN information of the terminal equipment.

Wherein the first information relates to the HPLMN of the terminal device. Illustratively, the first information is introduced by the following three examples (e.g., examples 1-3):

example 1, the first information includes measurement configuration information. The measurement configuration information comprises information of a frequency point in the HPLMN of the terminal equipment and information of measurement interval duration of the frequency point.

Wherein, the HPLMN intermediate frequency point of the terminal equipment includes: and at least one frequency point of the communication system, such as the frequency point of the first communication system and/or the frequency point of the second communication system in the HPLMN of the terminal equipment. Wherein the first communication system and the second communication system are different. For example, the first communication system may be a 5G network, and the second communication system may be a 4G network, a 3G network, or a 2G network, and in this embodiment of the present application, only the first communication system is a 5G network, and the second communication system is a 4G network for example. In this case, the information of the frequency point in the HPLMN of the terminal device may include at least one of the following: information of the frequency point in NR-HPLMN, information of the frequency point in EUTRA-HPLMN. The information of the intermediate frequency point in the HPLMN of the terminal device may also have other names, for example, a measurement object (MeasObject) identifier, which is not limited in the embodiment of the present application.

The information of the measurement interval duration of the frequency point may include at least one of the following: NR-HPLMN measurement gap, EUTRA-HPLMN measurement gap. The measurement interval duration of the frequency bin may include at least one time unit, for example. Wherein, a time unit may be one or several symbols, one or several slots (slots), one or several micro slots (mini-slots), one or several subframes, or one or several frames, etc. The definition of symbols, minislots, slots, subframes, and frames in embodiments of the present application may refer to the relevant technical specifications of 3 GPP. The information of the measurement interval duration of the frequency point may also have other names, for example, be described as measurement gap configuration (MeasGapConfig), which is not limited in the embodiment of the present application.

Example 2, the first information includes indication information. Wherein, as a possible implementation manner, the indication information indicates that the HPLMN of the terminal device is started to search. Illustratively, the indication information includes an HPLMN ID to indicate which PLMN to search for. As another possible implementation, the indication information indicates the HPLMN that is already in proximity to the terminal device. In this case, after the first access network device performs S701, the first access network device determines, based on the location of the area where the first access network device is located and the coverage area of the HPLMN identified by the HPLMN information, a separation distance between the first access network device and the HPLMN coverage area, and if the separation distance is smaller than a certain preset value, considers that the first access network device is the HPLMN that is already close to the terminal device. Correspondingly, the first access network equipment generates the indication information.

Example 3, the first information includes a cell selection policy. Wherein the cell selection policy is also related to the current access of the terminal device to the PLMN. Illustratively, the cell selection policy indicates that the reselection priority of the first cell in the HPLMN of the terminal device is higher than the reselection priority of the second cell in the PLMN to which the terminal device is currently accessing.

The communication systems of the first cell and the second cell may be the same or different, which is not limited in the embodiment of the present application.

It should be understood that the cell selection policy may have other names, such as Radio Frequency Selection Policy (RFSP), and the embodiments of the present application are described only by way of example of the cell selection policy.

It should be noted that, in other scenarios, the cell selection policy may also indicate at least one of the following:

the first item, the reselection priority of the first cell in the HPLMN of the terminal device is lower than the reselection priority of the second cell in the PLMN to which the terminal device is currently connected.

The second item, the reselection priority, is the same, and it is understood that the reselection priority of the first cell in the HPLMN of the terminal device is the same as the reselection priority of the second cell in the PLMN to which the terminal device is currently connected.

The two cell selection policies may be configured based on policies of different network operators. By way of example, the policies may include charging policies, and the reselection priorities are configured based on charging policies of different network operators such that the terminal device preferably resides in a network with a lower charging policy. It should be understood that the policies may also be implemented as other policies, which are not described in detail herein.

S703, the first access network equipment sends first information to the terminal equipment. Correspondingly, the terminal device receives the first information from the first access network device.

Illustratively, the message conveying the first information is presented as follows:

when the first information includes measurement configuration information, the first access network device sends the measurement configuration information to the terminal device through an RRC reconfiguration (RRC Reconfiguration) message.

When the first information includes indication information, the first access network device transmits the indication information to the terminal device through an RRC reconfiguration message or an RRC Release (RRC Release) message.

When the first information includes a cell selection policy, the first access network device transmits the cell selection policy to the terminal device through an RRC release message. Illustratively, the RRC release message includes a cell reselection priority (cell Reselection Priorities) field. The RRC release message transmits the cell selection policy through the cell reselection priority field.

It should be noted that, for the first access network device, after the first access network device performs S701, the first access network device determines that the first access network device is close to the HPLMN coverage area based on the location of the area where the first access network device is located and the coverage area of the HPLMN identified by the HPLMN information, if the distance between the location where the first access network device is located and the HPLMN coverage area is smaller than a certain preset value, then the first access network device performs S702 and S703. Otherwise, if the distance between the location of the first access network device and the HPLMN coverage area is greater than or equal to the preset value, the first access network device does not execute S703.

For the terminal device, after the terminal device performs S703, when the first information includes the instruction information, the terminal device performs S704a as shown in the block described in case 1 in fig. 7. When the first information includes a cell selection policy, the terminal device performs S704b as shown in the block described in case 2 in fig. 7. When the first information includes measurement configuration information, the terminal device performs S704c as shown in the block described in case 3 in fig. 7. The descriptions of S704a, S704b, and S704c are as follows:

s704a, the terminal equipment starts searching the HPLMN of the terminal equipment according to the first information so that the terminal equipment is accessed to the HPLMN in a switching or redirection mode.

The first information in S704a may be implemented as the indication information in S703.

The manner of switching in S704a refers to that the terminal device is switched from the cell currently accessed to the PLMN to the cell in the HPLMN of the terminal device, and the implementation process of switching can refer to related technologies, which are not described herein.

The redirection in S704a refers to a process that the terminal device releases the connection in the current access PLMN, and re-accesses the HPLMN and redirects, which can be referred to the related art and will not be described herein.

And S704b, the terminal equipment searches and resides in the HPLMN of the terminal equipment according to the cell selection strategy in the first information.

Illustratively, the terminal device preferentially selects a frequency point of searching the HPLMN to camp on the HPLMN based on the cell selection policy. Alternatively, the terminal device preferentially resides in the HPLMN based on the cell selection policy and the measurement result. The process of searching for the frequency point and residing in the mobile terminal may refer to related technology, and will not be described herein.

And S704c, the terminal equipment performs different network measurement according to the measurement configuration information in the first information so as to obtain a measurement result.

The measurement configuration information includes, for example, measurement configuration of different networks, such as frequency points in the HPLMN, or measurement interval duration of the frequency points, so that the terminal device can determine which frequency point(s) to measure and which time domain resource(s) to measure the frequency points based on the measurement configuration information, thereby obtaining measurement results.

Optionally, in some embodiments, as shown in fig. 10, after the terminal device performs S704c, S705 is further performed:

and S705, the terminal equipment sends a measurement report to the first access network equipment. Correspondingly, the first access network equipment receives a measurement report from the terminal equipment.

The measurement report in S705 is, for example, a report generated by the terminal device based on the measurement result in S704 c.

S706, the first access network equipment determines a target cell according to the measurement report and the priority information.

The target cell is a cell to be switched or redirected by the terminal equipment, and is a cell in the HPLMN.

The priority information indicates that the priority of the cell in the HPLMN of the terminal equipment is higher than the priority of the cell in the current access PLMN of the terminal equipment. The priority information may be preconfigured or may be information provided by the first core network device to the first access network device, which is not limited by the embodiment of the present application.

The measurement report includes, for example, the signal quality measurement of cell 1 and the signal quality measurement of cell 2. Wherein cell 1 is the cell in the PLMN to which the terminal equipment is currently accessing, and cell 2 is the cell in the HPLMN. In case that the signal quality measurement results of the cell 1 and the cell 2 are the same, or the signal quality measurement result of the cell 1 is better than the signal quality measurement result of the cell 2, but the signal quality measurement result of the cell 2 also meets the requirement, the first access network device determines that the target cell is the cell 2 based on the priority information.

S707, the first access network device sends a first message to the terminal device. Correspondingly, the terminal device receives a first message from the first access network device.

Wherein the first message includes information of the target cell. The target cell in S707 is identical to the target cell in S706, and will not be described here. The first message may be a handover message to indicate that the target cell is a cell to be handed over. Alternatively, the first message may be an RRC release message to indicate that the target cell is a redirected cell. It should be understood that the first message may be other messages, which embodiments of the present application do not limit.

After the terminal device performs S707, the terminal device may switch or redirect to the target cell.

In this way, the target cell is a cell determined by the first access network device based on the priority information, and in the case that the cell priority of the HPLMN is higher than the cell priority in the PLMN to which the terminal device is currently connected, the terminal device can be preferentially handed over (or redirected) to the cell in the HPLMN, so that the terminal device is handed over (or redirected) from the PLMN to which the terminal device is currently connected to the HPLMN.

In some embodiments, the terminal device moves in the current access PLMN (i.e. visited network). In this mobile scenario, two access network devices are involved, namely a first access network device and a second access network device. Wherein the first access network device and the second access network device are different access network devices. The first access network device may be referred to as a source access network device, i.e. an access network device to which the terminal device accesses before moving, and may be referred to as an S-RAN. Accordingly, the second access network device may be used as a target access network device, i.e. an access network device to which the terminal device accesses after moving, and may be denoted as T-RAN. Referring to fig. 11a or 11b, the specific steps are as follows:

S21, the terminal equipment sends a measurement report to the S-RAN equipment (measurement report). Accordingly, the S-RAN device receives a measurement report from the terminal device.

The measurement report is obtained after the terminal device performs measurement based on the measurement configuration information, or the measurement report is obtained by the terminal device measuring the frequency point currently accessed to the PLMN, which may be referred to in the related art and will not be described herein.

The sending timing of the measurement report may refer to related technologies, for example, the terminal device sends under a certain triggering condition, or sends according to a certain period, which is not limited in the embodiment of the present application.

For example, the implementation procedure of S21 may refer to the description of S705, which is not repeated herein.

For the S-RAN apparatus, the S-RAN apparatus determines a target cell based on the measurement report to perform handover. If the target cell does not have an Xn interface between the T-RAN equipment and the S-RAN equipment, the switching is based on the switching flow of the N2 interface. Otherwise, if there is an X2/Xn interface between the T-RAN device and the S-RAN device corresponding to the target cell, the handover belongs to a handover procedure based on X2/Xn.

Taking a 5G network as an example, the switching flow based on the N2 interface is as follows:

S22, the S-RAN equipment sends a switching requirement (handover required) message to the S-AMF network element. Correspondingly, the S-AMF network element receives a handover request message from the terminal device.

The S-AMF network element is in communication connection with the S-RAN equipment, for example, the S-AMF network element is connected with the S-RAN equipment through an N2 interface.

Wherein the handover required message is used to request handover to the target cell. The determination of the target cell may be referred to in S706, and will not be described here again.

The handover required message may, for example, carry HPLMN information of the terminal device, which may be carried in a container (e.g., source to target transparent container) that the S-RAN device sends to the T-RAN device and is carried in the handover required message. For the S-RAN device, the procedure for acquiring HPLMN information may refer to the description of S701, which is not repeated herein. Of course, the handover request message may not carry the HPLMN information of the terminal device, that is, the container does not include the HPLMN information of the terminal device, or the handover request message does not carry the container, which is not limited in the embodiment of the present application.

For the S-AMF network element, the S-AMF network element selects a T-AMF network element based on the switching requirement message, wherein the T-AMF network element is connected with the T-RAN equipment through an N2 interface. The S-AMF network element performs S23:

S23, the S-AMF network element sends a request message for creating the user equipment context to the T-AMF network element. Correspondingly, the T-AMF network element receives a context request message of the creation user equipment from the S-AMF network element.

Illustratively, in the case where the handover required message carries the HPLMN information of the terminal device via a container, creating the user device context request message also includes the container described above. On the contrary, in the case that the handover request message does not carry the HPLMN information of the terminal device, the user equipment context request is created without carrying the HPLMN information of the terminal device.

S24, when the T-AMF network element determines that the terminal equipment is in a roaming state, the T-AMF network element sends a handover request (handover request) message to the T-RAN equipment. Correspondingly, the T-RAN equipment receives a switching request message from the T-AMF network element.

Illustratively, the T-AMF network element determines that the terminal device is in a roaming state based on the MCC and MNC in the sui of the terminal device.

Wherein the handover request message includes HPLMN information of the terminal device and PLMN information of the terminal device registered. Illustratively, the HPLMN information of the terminal device includes the HPLMN ID of the terminal device, and PLMN information registered with the terminal device, e.g., UE registered PLMN ID.

In the case where the user equipment context request message is created to carry the HPLMN information of the terminal equipment through the container, the handover request message also carries the HPLMN information of the terminal equipment through the container. On the contrary, in the case that the user equipment context request message is created without carrying the HPLMN information of the terminal equipment, the T-AMF network element adds the HPLMN information of the terminal equipment stored in itself in the handover request message.

S25, terminal equipment, S-RAN equipment, T-RAN equipment, S-AMF network elements and T-AMF network elements execute a switching flow based on an N2 interface together.

The implementation process of S25 may refer to the related art, and will not be described herein.

Thus, for the T-RAN device, the T-RAN device may obtain HPLMN information of the terminal device from the T-AMF network element through the N2 handover procedure.

Taking a 5G network as an example, the switching flow based on the Xn interface is as follows:

s26, the S-RAN device sends a handover request message to the T-RAN device. Accordingly, the T-RAN device receives a handover request message from the S-RAN device.

S27, terminal equipment, S-RAN equipment, T-RAN equipment, S-AMF network elements and T-AMF network elements execute a switching flow based on an Xn interface together.

The implementation process of S27 may refer to the related art, and will not be described herein.

Thus, for the T-RAN device, the T-RAN device may obtain HPLMN information of the terminal device from the S-RAN network element through an Xn interface based handover procedure.

In fig. 11a and 11b, the S-AMF network element and the T-AMF network element may be the same core network device or different core network devices, which is not limited in this embodiment of the present application.

For the T-RAN device, after acquiring HPLMN information of the terminal device based on the above-mentioned switching procedure of N2 or the above-mentioned switching procedure of Xn, the T-RAN device performs S28 and S29:

and S28, the T-RAN equipment determines third information according to the HPLMN information of the terminal equipment.

Wherein the third information relates to the HPLMN of the terminal device. For example, the third information may refer to the description of the first information in S702, which is not described herein.

And S29, the T-RAN equipment transmits third information to the terminal equipment. Accordingly, the terminal device receives the third information from the T-RAN device.

The implementation process of S29 may refer to the description of S703, which is not described herein. For the terminal device, after S29 is performed, S704a, S704b, or S704c may be performed, which will not be described herein.

It should be understood that fig. 11a only illustrates a 5G network as an example, and shows a switching flow based on an N2 interface. In the 4G network, the Xn interface is replaced by an X2 interface, the AMF network element is replaced by an MME, and the processing procedure of fig. 11a is equally applicable. Similarly, fig. 11b only illustrates a 5G network as an example, and shows a handover procedure based on an Xn interface. In the 4G network, the Xn interface is replaced by an X2 interface, that is, the switching procedure based on the Xn interface is replaced by a switching procedure based on the X2 interface. The above-mentioned AMF network element, instead of MME, the procedure of fig. 11b is equally applicable.

In this way, even if the terminal device is switched from the cell of the S-RAN device (i.e., the first access network device) to the cell of the T-RAN device (i.e., the second access network device), the second access network device can timely determine the third information, so that the terminal device performs switching, redirection or reselection based on the third information, thereby accessing to the HPLMN, shortening or eliminating the service transmission interruption time, and helping to improve the user experience.

Example two

The second embodiment will be described with reference to fig. 12 to 21. The second embodiment may be a second communication method provided in the embodiments of the present application.

In the second communication method provided by the embodiment of the present application, the terminal device receives first information from an access network device of a first PLMN, where the first PLMN is a PLMN currently accessed by the terminal device, the first information is used for the terminal device to determine to search for a second PLMN, and the first PLMN is different from the second PLMN. The terminal device searches for and resides in the second PLMN based on the first information. In this way, the first information can enable the terminal equipment to determine the time for searching the second PLMN, so that the terminal equipment can also search and reside in the second PLMN in time, the terminal equipment can reside in the second PLMN from the first PLMN in time, the service transmission interruption time is shortened or eliminated, normal transmission of the service is ensured, and the user experience is improved.

As shown in fig. 12, a second communication method 1200 provided in an embodiment of the present application includes the following steps:

s1201, the access network equipment of the first PLMN sends first information to the terminal equipment. Correspondingly, the terminal device receives the first information from the access network device of the first PLMN.

The first PLMN is a PLMN to which the terminal equipment is currently accessed.

Wherein the first information is used for the terminal device to determine to search for the second PLMN. Illustratively, the first information includes information of a location area where the access network device is located, as described in detail in example a and example B. Alternatively, the first information includes second PLMN information, such as an ID of the second PLMN, as detailed in example C and example D.

Wherein the first PLMN is different from the second PLMN. Illustratively, the first PLMN includes an HPLMN of the terminal equipment and the second PLMN includes an EPLMN of the terminal equipment, see for details the description of example a and example C. In this case, the access network device in S1201 is replaced with the first access network device. Alternatively, the first PLMN comprises an EPLMN of the terminal equipment and the second PLMN comprises an HPLMN of the terminal equipment, see for details the description of example B and example D. In this case, the access network device in S1201 is replaced with the second access network device.

In the second communication method 1200 according to the embodiment of the present application, the HPLMN and the EPLMN are different networks from each other. That is, the foreign network includes the EPLMN of the terminal device relative to the HPLMN of the terminal device. The foreign network comprises the HPLMN of the terminal device relative to the EPLMN of the terminal device.

And S1202, the terminal equipment searches and resides in the second PLMN according to the first information.

For example, when the first information includes information of a location area where the access network device is located, the implementation procedure of S1202 may be referred to the introduction of example a and example B. Alternatively, when the first information includes the second PLMN information, the implementation procedure of S1202 may be referred to the description of example C and example D.

Next, description will be made of example a, example B, example C, and example D, respectively:

example a, the first information comprises information of a location area where the third access network device is located, the first PLMN comprises an HPLMN of the terminal device, and the second PLMN comprises an EPLMN of the terminal device. That is, the terminal device resides from the HPLMN to the EPLMN, and the terminal device determines whether to search for the second PLMN (i.e., EPLMN) based on the location area in which the third access network device is located.

As shown in fig. 13, the steps of example a are described as follows:

And S1203a, the third core network device in the HPLMN sends information A2 to the terminal device. Correspondingly, the terminal device receives information A2 from a third core network device in the HPLMN.

Wherein the third core network device is a core network device in the HPLMN. The third core network device may be an MME of a 4G network or an AMF network element of a 5G network, and of course, the third core network device may be a core network device in another communication system network, which is not limited in the embodiment of the present application. In the embodiment of the present application, only the MME of the 4G network or the AMF network element of the 5G network is taken as an example for introduction.

Wherein the terminal device is in a connected state when executing S1203 a.

Wherein the information A2 comprises area information covered by the second PLMN, i.e. area information covered by the EPLMN.

Illustratively, the EPLMN in information A2 may be denoted as the target EPLMN. Wherein the target EPLMN satisfies at least one of the following preset conditions:

the target EPLMN overlaps the HPLMN coverage area, preset condition a 1.

The condition a2 is preset, and the target EPLMN is close to the HPLMN coverage area. Wherein the target EPLMN is adjacent to the HPLMN coverage area, it being understood that the coverage area of the target EPLMN is tangential to the coverage area of the HPLMN; or, there is no overlapping area between the coverage area of the target EPLMN and the coverage area of the HPLMN, and the coverage area of the target EPLMN and the coverage area of the HPLMN are not tangential, but the interval between the coverage area of the target EPLMN and the coverage area of the HPLMN is smaller than a certain preset value.

The preset condition a3 is that the coverage area of the target EPLMN overlaps with the service area of the third core network device.

And (4) presetting a condition a4, wherein the coverage area of the target EPLMN is close to the service area of the third core network equipment. The coverage area of the target EPLMN is close to the service area of the third core network device, which can be understood as that the coverage area of the target EPLMN is tangential to the service area of the third core network device; or, there is no overlapping area between the coverage area of the target EPLMN and the service area of the third core network device, and the coverage area of the target EPLMN and the service area of the third core network device are not tangential, but the interval between the coverage area of the target EPLMN and the service area of the third core network device is smaller than a certain preset value.

It should be understood that the above preset conditions A1 to a4 are only exemplary preset conditions satisfied by the target EPLMN in the information A1, and of course, other descriptions may be provided for the preset conditions satisfied by the target EPLMN in the information A1, which is not limited in this embodiment of the present application.

Illustratively, still taking the target EPLMN as an example, the area in information A2 may include the entire area covered by the target EPLMN. The whole area covered by the target EPLMN is described as follows: the target EPLMN coverage area may be a physically corresponding geographic area, such as a remote area in china. Illustratively, taking the china mobile operator as an example, the area where the china mobile operator provides network sharing services to other network operators, such as china corporation, china telecommunications, etc., includes city a. In this case, the area covered by a certain EPLMN includes city a. The EPLMN coverage area may also have other names, such as an effective area of the EPLMN, and in this embodiment of the present application, the EPLMN coverage area is only used as an example for introduction.

For the target EPLMN, the coverage area is characterized as follows: the area covered by the target EPLMN may be represented by a set of location areas or administrative areas. For example, taking an EPLMN coverage area including city a as an example, the set of areas planned by the chinese mobile operator in city a is denoted 00000-09999. Wherein 00000 represents county 1 of city a, 00001 represents county 2 of city a, 00002 represents county 3 of city a, and the like, and the details are not repeated. For another example, the area covered by some EPLMN includes city B, and the set of areas planned by the chinese mobile operator in city B is denoted 10000-19999. 10000 represents county 1 of city B, 10001 represents county 2 of city B, 10002 represents county 3 of city B, and the like, and will not be repeated. It should be understood that, as the communication technology evolves, other characterization methods are possible and should not be construed as limiting the embodiments of the present application.

Alternatively, the area in the information A2 may include a partial area covered by the target EPLMN, such as one of the following:

first, overlap region. The overlapping area is an area where a service area of the third core network device overlaps with a coverage area of the target EPLMN. Illustratively, the set of regions included in information A2 is denoted as {00000, 00001, 00002, 00003}. In this case, the above overlapping area includes county 1, county 2, county 3, and county 4 of city a.

Second, boundary region. Wherein the boundary region is a region in the overlap region in which a distance from a boundary of the overlap region is smaller than a threshold value a 1. Illustratively, the set of regions included in information A2 is denoted as {00000, 00001, 00002}. In this case, the above overlapping area includes county 1, county 2, and county 3 of city a. For example, referring to fig. 14e, the upper half of the annular region represents the boundary region indicated by the information A2.

Third, first region. Wherein the first area is an area in which a distance from the terminal device is smaller than the threshold a2 in the above-mentioned boundary area. Illustratively, the set of regions included in information A2 is denoted as {00000, 00001}. In this case, the above overlapping area includes county 1 and county 2 of city a. As shown in fig. 14e, the terminal device may be located in the above-mentioned boundary area or may be located outside the boundary area. For example, referring to fig. 14e, the position indicated by the triangle indicates the position where the terminal device is located. The areas having a distance from the terminal device smaller than the threshold a2 can be expressed as an area x, an area y, and an area z. The region x, the region y, and the region z overlap with the upper half of the annular region, respectively, representing the first region indicated by the information A2.

For the third core network device, the information A2 may be preconfigured, or may be information autonomously determined by the third core network device, which is not limited in the embodiment of the present application.

Optionally, the implementation procedure of S1203a includes the following four examples:

example 1, taking the initial attach procedure of the 4G network as an example, the steps are as shown in fig. 14 a:

first, the terminal device transmits an Attach Request (Attach Request) message to a third core network device in the HPLMN. Correspondingly, the third core network device in the HPLMN receives the attach request message from the terminal device.

Wherein the third core network device may be implemented as an MME.

Then, the third core network device in the HPLMN transmits information A2 to the terminal device through an Attach accept (Attach accept) message. Correspondingly, the terminal device receives the information A2 from the third core network device in the HPLMN through the attach accept message.

That is, the attach accept message includes information A2.

It should be appreciated that the initial attach procedure of the 4G network may be referred to the 3GPP related technical specifications, and will not be described here again.

In this way, the terminal device can acquire the information A2 in the 4G network registration process of the HPLMN to determine whether the terminal device is in the area covered by the EPLMN, so as to search for and reside in the EPLMN in time.

Example 2, taking the TAU procedure of the 4G network as an example, the steps are as shown in fig. 14 b:

first, the terminal device sends a TAU request (TAU request) message to a third core network device in the HPLMN. Correspondingly, the third core network device in the HPLMN receives the TAU request message from the terminal device.

Wherein the third core network device may be implemented as an MME.

Then, the third core network device in the HPLMN sends information A2 to the terminal device through a TAU accept (TAU accept) message. Correspondingly, the terminal device receives the information A2 from the third core network device in the HPLMN through the TAU accept message.

That is, the TAU accept message includes information A2.

It should be appreciated that the TAU procedure of the 4G network may be referred to the 3GPP related technical specifications, and will not be described here again.

In this way, the terminal device can acquire the information A2 in the TAU process of the HPLMN to determine whether the terminal device is in the area covered by the EPLMN, so as to search for and reside in the EPLMN in time.

Example 3, taking the registration procedure of the 5G network as an example, the steps are as shown in fig. 14 c:

first, the terminal device sends a registration request (Registration request) message to a third core network device in the HPLMN. Correspondingly, the third core network device in the HPLMN receives the registration request message from the terminal device.

The third core network device may be implemented as an AMF network element.

The third core network device in the HPLMN then sends information A2 to the terminal device via a registration accept (Registration accept) message. Correspondingly, the terminal equipment receives the information A2 from the third core network equipment in the HPLMN through the registration acceptance message.

That is, the registration acceptance message includes information A2.

It should be appreciated that the registration procedure of the 5G network may refer to the 3GPP related technical specifications, and will not be described here again.

In this way, the terminal device can acquire the information A2 in the 5G network registration process of the HPLMN to determine whether the terminal device is in the area covered by the EPLMN, so as to search for and reside in the EPLMN in time.

Example 4, taking the configuration update procedure of the 5G network as an example, the steps are as shown in fig. 14 d:

the third core network device in the HPLMN sends information A2 to the terminal device via a user equipment configuration update (UE configuration update) message. Correspondingly, the terminal device receives the information A2 from the third core network device in the HPLMN through the user device configuration update message.

The third core network device may be implemented as an AMF network element.

That is, the user equipment configuration update message includes information A2.

It should be appreciated that the configuration update procedure of the 5G network may be referred to the 3GPP related technical specifications, and will not be described here again.

In this way, the terminal device can acquire the information A2 in the configuration updating process of the 5G network of the HPLMN to determine whether the terminal device is in the area covered by the EPLMN, so as to search for and reside in the EPLMN in time.

Note that S1203a described above is an optional step. The terminal device may not execute S1203a. For example, the terminal device may also locally preconfigure the above information A2, which is not limited in the embodiment of the present application.

Accordingly, as shown in fig. 13, S1201 is implemented as S1201a:

and S1201a, the third access network equipment in the HPLMN sends information A1 to the terminal equipment. Correspondingly, the terminal device receives information A1 from the third access network device in the HPLMN.

Wherein the information A1 includes information of a location area where the third access network device is located.

Illustratively, information A1 is carried in a system message. That is, the terminal device is in an idle state when executing S1201 a. For example, the terminal equipment is at the edge of the HPLMN coverage area and the signal quality is poor. The third access network device in the HPLMN sends information A1 to the terminal device through a system message. Correspondingly, the terminal equipment receives information A1 from the third access network equipment in the HPLMN through the system message.

In the case where S1203a is executed, the terminal apparatus executes S1203a first and then S1201a. For example, the terminal device receives information A2 from a third core network device of the HPLMN when in a connected state within the coverage area of the HPLMN. When the terminal equipment moves to the edge of the HPLMN coverage area, the terminal equipment receives the information A1, and then combines the information A1 and the information A2 to determine whether the terminal equipment is in the area indicated by the information A2.

Accordingly, as shown in fig. 13, S1202 is implemented as step a1 and step a2:

and a step a1, the terminal equipment determines that the terminal equipment is in the area indicated by the information A2 according to the area where the third access network equipment is and the information A2.

For example, if the area where the third access network device is located belongs to the area indicated by the information A2, the terminal device considers that the terminal device is located in the area indicated by the information A2.

Step A2, searching and residing in the EPLMN when the terminal equipment is in the area indicated by the information A2.

For example, still taking a PLMN in the EPLMN, such as the target EPLMN, as an example, when the terminal device is in the area indicated by the information A2, the terminal device searches for a frequency point of the target EPLMN and then resides in the target EPLMN, which may be referred to in the related art, and will not be described herein.

It should be noted that, step a2 may be unconditionally triggered, or may be performed by the terminal device when a certain trigger condition is met. Wherein the triggering condition of step a2 includes a triggering condition a1. The trigger condition a1 is described as follows:

the communication system of the HPLMN accessed by the terminal equipment at present is lower than the communication system of the target EPLMN in the information A1. The communication system of the HPLMN to which the terminal device is currently connected may be, for example, a 4G network of the HPLMN. The communication system of the target EPLMN in the information A1 may be a 5G network of the target EPLMN. In this case, after the terminal device resides in the 5G network of the target EPLMN, better data transmission performance can be achieved. It should be understood that the triggering conditions of step a2 may also include other triggering conditions, which are not described in detail herein.

In this way, in the scenario of example a, the terminal device determines, based on the location area where the third access network device is located, whether the terminal device is in the coverage area of the EPLMN, if so, the terminal device searches for the EPLMN in time, so that the terminal device switches from the HPLMN to the EPLMN in time, the occurrence probability of the network drop problem is reduced, and the service transmission interruption time is shortened or eliminated, thereby improving the user experience.

Example B, the first information comprises information of a location area where the first access network device is located, the first PLMN comprises an EPLMN of the terminal device, and the second PLMN comprises an HPLMN of the terminal device. That is, the terminal device resides from the EPLMN to the HPLMN, and the terminal device determines whether to search for the second PLMN (i.e., the HPLMN) based on the location area in which the first access network device is located.

As shown in fig. 15, the steps of example B are described as follows:

and S1203B, the first core network device in the EPLMN sends information B2 to the terminal device. Correspondingly, the terminal equipment receives information B2 from the first core network equipment in the EPLMN.

Wherein the information B2 comprises information of a partial coverage area of the first PLMN, i.e. information of an EPLMN partial coverage area. The partial coverage area in the information B2 belongs to the border area of the first PLMN, i.e. to the border area of the EPLMN.

Note that, with respect to the area covered by the EPLMN, reference may be made to the description of the noun explanation. For a certain EPLMN, the boundary area of the EPLMN may be understood as an area where the distance from the edge of the EPLMN coverage area is smaller than a certain preset value, based on the edge of the EPLMN coverage area, in the whole area covered by the EPLMN, such as the diagonal line filling portion of fig. 16.

Illustratively, taking a certain EPLMN as an example, the area in the information B2 includes at least one of the following:

first, overlap region. The overlapping area is an area where a service area of the first core network device overlaps with a boundary area of the target EPLMN.

A second item, a first region. Wherein the first area is an area in which a distance from the terminal device in the above overlapping area is smaller than the threshold b 1.

The information B2 may be preconfigured or may be information autonomously determined by the first core network device, which is not limited in the embodiment of the present application.

Optionally, the implementation procedure of S1203b includes the following examples:

taking the registration procedure of the 5G network as an example, the steps are as shown in fig. 17:

first, the terminal device sends a registration request (registration request) message to a first core network device in the EPLMN. Correspondingly, the first core network device in the EPLMN receives a registration request message from the terminal device.

The first core network device may be implemented as an AMF network element.

Then, the first core network device in the EPLMN transmits information B2 to the terminal device through a registration accept (registration accept) message. Correspondingly, the terminal equipment receives the information B2 from the first core network equipment in the EPLMN through the registration acceptance message.

That is, the registration acceptance message includes information B2.

In this way, the terminal device can acquire the information B2 in the 5G network registration process of the HPLMN, so as to determine whether the terminal device is in the boundary area of the EPLMN, thereby searching and residing in the HPLMN in time.

Accordingly, as shown in fig. 15, S1201 is implemented as S1201b:

and S1201B, the first access network equipment in the EPLMN sends information B1 to the terminal equipment. Correspondingly, the terminal equipment receives information B1 from the first access network equipment in the EPLMN.

Illustratively, information B1 is carried in a system message. That is, the terminal device is in an idle state when executing S1201b. For example, the terminal equipment is at the edge of the EPLMN coverage area and the signal quality is poor. The first access network device in the EPLMN sends information B1 to the terminal device through a system message. Correspondingly, the terminal equipment receives the information B1 from the first access network equipment in the EPLMN through the system message.

In the case where S1203b is executed, the terminal apparatus executes S1203b first and then S1201b. For example, the terminal device receives the information B2 from the first core network device of the EPLMN when in the connected state within the coverage area of the EPLMN. When the terminal equipment moves to the edge of the EPLMN coverage area, the terminal equipment receives the information B1, and further combines the information B1 and the information B2 to determine whether the terminal equipment is in the area indicated by the information B2.

Accordingly, as shown in fig. 15, S1202 is implemented as step b1 and step b2:

and B1, the terminal equipment determines that the terminal equipment is in the area indicated by the information B2 according to the area where the first access network equipment is and the information B2.

For example, if the area where the first access network device is located belongs to the area indicated by the information B2, the terminal device considers that the terminal device is located in the area indicated by the information B2.

Step B2, searching and residing in the HPLMN when the terminal equipment is in the area indicated by the information B2.

For example, when the terminal device is in the area indicated by the information B2, the terminal device searches for the frequency point of the HPLMN and then resides in the HPLMN, which may be referred to in the related art, and will not be described herein.

In this way, in the scenario of example B, the terminal device determines, based on the location area where the first access network device is located, whether the terminal device is located in the boundary area of the EPLMN, if so, the terminal device searches for the HPLMN in time, so that the terminal device switches from the EPLMN to the HPLMN in time, the occurrence probability of the network drop problem is reduced, and the service transmission interruption time is shortened or eliminated, thereby improving the user experience.

Example C, the first information includes second PLMN information, i.e., PLMN information of the foreign network. The first PLMN comprises an HPLMN of the terminal equipment and the second PLMN comprises an EPLMN of the terminal equipment. That is, the terminal device switches from the HPLMN to its EPLMN, and the terminal device determines whether to search for the second PLMN (i.e., EPLMN) based on the second PLMN information.

As shown in fig. 18, the steps of example C are described as follows:

as shown in fig. 18, S1201 is implemented as S1201c:

and S1201C, the third access network equipment in the HPLMN sends information C1 to the terminal equipment. Correspondingly, the terminal device receives information C1 from the third access network device in the HPLMN.

Wherein the information C1 comprises second PLMN information, i.e. EPLMN information, such as EPLMN ID. That is, the information C1 carries heterogeneous network information. The foreign network information in the information C1 may be understood as information of a PLMN different from the PLMN to which the third access network device belongs. For example, the PLMN to which the third access network device belongs is an HPLMN, in which case the information C1 comprises an EPLMN ID.

Illustratively, a PLMN in the EPLMN is designated as the target EPLMN. Taking the information C1 including the information of the target EPLMN as an example, the description will be made. Wherein the target EPLMN in the information C1 satisfies one or more of the following preset conditions:

the preset condition c1 and the target EPLMN are close to the third access network device. The target EPLMN is close to the third access network device, which can be understood that the distance between the location of the area where the third access network device is located and the reference point of the coverage area of the target EPLMN is smaller than a certain preset value. The reference point may be a center point of the target EPLMN coverage area, or a point on an edge of the target EPLMN coverage area, which is not limited in the embodiment of the present application.

The preset condition c2, the target EPLMN, and the HPLMN coverage area overlap.

It should be understood that the preset conditions C1 and C2 are only exemplary preset conditions met by the target EPLMN in the information C1, and of course, other descriptions may be provided for the preset conditions met by the target EPLMN in the information C1, which is not limited in this embodiment of the present application.

Alternatively, the information C1 may be carried in a system message. In this case, S1201c may be implemented as: and the third access network equipment in the HPLMN sends information C1 to the terminal equipment through a system message. Correspondingly, the terminal equipment receives the information C1 from the third access network equipment in the HPLMN through the system message.

Illustratively, as one possible implementation, the system message includes a plurality of system information blocks (system information block, SIBs). The information C1 may be carried in at least one of the following SIBs:

the first term, the first SIB. The first SIB is used for bearing the same-frequency information, the same-frequency information comprises frequency point information in the target EPLMN, and the frequency point in the same-frequency information is the same as the frequency point of the cell where the terminal equipment currently resides. The first SIB may be SIB3 specified in the 3GPP related technical specification, for example.

The second term, the second SIB. The second SIB is used for carrying inter-frequency information, the inter-frequency information comprises frequency point information in the target EPLMN, and the frequency point in the inter-frequency information is different from the frequency point of the cell where the terminal equipment currently resides. The second SIB may be SIB4 specified in the 3GPP related technical specification, for example.

Third, third SIB. The third SIB is an SIB for carrying inter-system information, the inter-system information includes information of a communication system of the target EPLMN, and the communication system of the inter-system information is different from a communication system of a cell where the terminal device currently resides. The third SIB may be SIB5 specified in the 3GPP related technical specification, for example.

As another possible implementation, the system message may be a dedicated system message, dedicated to transmitting the information C1.

As shown in fig. 18, S1202 is implemented as step c1:

and c1, searching and residing in the EPLMN by the terminal equipment according to the second PLMN information.

Wherein the second PLMN information in step c1 includes target EPLMN information, such as PLMN ID of the target EPLMN.

The terminal device determines, based on the second PLMN information, a PLMN identified by the second PLMN information. In the case that the terminal device determines that the PLMN is its own EPLMN, searching the frequency point of the PLMN and then camping on the PLMN, the specific reference may be made to the related art, which is not described herein again.

In this way, in the scenario of example C, the terminal device searches for and resides in the corresponding EPLMN based on the received heterogeneous network information, such as the EPLMN ID carried in the information C1, so as to reduce the occurrence probability of the network drop problem, shorten or eliminate the service transmission interruption time, and thereby improve the user experience.

Example D, the first information includes second PLMN information, i.e., PLMN information of the foreign network. The first PLMN comprises an EPLMN of the terminal equipment and the second PLMN comprises an HPLMN of the terminal equipment. That is, the terminal device switches from the EPLMN to the HPLMN, and the terminal device determines whether to search for the second PLMN (i.e., HPLMN) based on the second PLMN information.

As shown in fig. 19, the steps of example D are described as follows:

as shown in fig. 19, S1201 is implemented as S1201d:

and S1201D, the first access network equipment in the EPLMN sends information D1 to the terminal equipment. Correspondingly, the terminal device receives the information D1 from the first access network device in the EPLMN.

Wherein the information D1 comprises second PLMN information, i.e. HPLMN information, such as HPLMN ID. That is, the information D1 carries heterogeneous network information. The heterogeneous network information in the information D1 may be understood as information of a PLMN different from the PLMN to which the first access network device belongs. For example, the PLMN to which the first access network device belongs is an EPLMN, in which case the information D1 includes an HPLMN ID.

Illustratively, the first access network is configured to execute S1201d when the HPLMN satisfies one or more of the following preset conditions. The preset conditions are as follows:

the preset conditions d1 and HPLMN are close to the first access network equipment. The HPLMN is adjacent to the first access network device, which is understood that the distance between the location of the area where the first access network device is located and the reference point of the HPLMN coverage area is smaller than a certain preset value. The reference point may be a center point of the HPLMN coverage area, or a point on an edge of the HPLMN coverage area, which is not limited in the embodiment of the present application.

The preset conditions d2 and the HPLMN overlap with the coverage area of the EPLMN to which the first access network device belongs.

It should be understood that the above preset conditions D1 and D2 are only exemplary preset conditions satisfied by the HPLMN in the information D1, and of course, other descriptions may be provided for the preset conditions satisfied by the HPLMN in the information D1, which is not limited in this embodiment of the present application.

Alternatively, the information D1 may be carried in a system message. In this case, S1201d may be implemented as: the first access network device in the EPLMN sends information D1 to the terminal device. Correspondingly, the terminal device receives the information D1 from the first access network device in the EPLMN.

Illustratively, as one possible implementation, the system message includes a plurality of SIBs. The information D1 may be carried in at least one of the following SIBs:

the first term, the first SIB. The first SIB is used for carrying same-frequency information, the same-frequency information comprises frequency point information in the HPLMN, and the frequency point in the same-frequency information is the same as the frequency point of the cell where the terminal equipment currently resides. The first SIB may be SIB3 specified in the 3GPP related technical specification, for example.

The second term, the second SIB. The second SIB is used for carrying inter-frequency information, the inter-frequency information comprises frequency point information in the HPLMN, and the frequency point in the inter-frequency information is different from the frequency point of the cell where the terminal equipment currently resides. The second SIB may be SIB4 specified in the 3GPP related technical specification, for example.

Third, third SIB. The third SIB is an SIB for carrying inter-system information, the inter-system information includes information of a communication system of the HPLMN, and the communication system of the inter-system information is different from a communication system of a cell where the terminal device currently resides. The third SIB may be SIB5 specified in the 3GPP related technical specification, for example.

As another possible implementation, the system message may be a dedicated system message, dedicated to transmitting the information D1.

As shown in fig. 19, S1202 is implemented as step d1:

and d1, searching and residing in the HPLMN by the terminal equipment according to the second PLMN information.

Wherein the second PLMN information in step d1 comprises HPLMN information, such as HPLMN ID.

The terminal device determines, based on the second PLMN information, an HPLMN identified by the second PLMN information. In the case that the terminal device determines that the PLMN is its own HPLMN, searching for a frequency point of the HPLMN and then camping on the HPLMN, for example, refer to related technologies, which will not be described herein.

In this way, in the scenario of example D, the terminal device searches for and resides in the corresponding HPLMN based on the received heterogeneous network information, such as the HPLMN ID carried in the information D1, so as to reduce the occurrence probability of the network drop problem, shorten or eliminate the service transmission interruption time, thereby improving the user experience.

The terminal device performs modulation and demodulation based on a protocol defined by the supported communication technology. The protocol specified by the communication technology in the embodiments of the present application may also be referred to as a communication protocol. The communication protocol stack is the sum of the communication protocols of the layers. For example, referring to fig. 20, a communication protocol stack at a terminal device side may be divided into a control plane and a user plane that are vertically arranged. The control plane is used for transmitting control signaling, and mainly comprises a non-access stratum (NAS) layer, a radio resource control (radio resource control, RRC) layer, a service data adaptation protocol (service data adaptation protocol, SDAP) layer, a packet data convergence protocol (packet data convergence protocol, PDCP) layer, a radio link control (radio link control, RLC) layer, a medium access control (media access control, MAC) layer, and a Physical (PHY) layer. The user plane is used for transmitting data information and mainly comprises an SDAP layer, a PDCP layer, an RLC layer, a MAC layer and a PHY layer. It should be understood that the protocol layers of the control plane and the user plane may be divided in different manners or the same manner under different communication technologies. Wherein, the RRC layer, SDAP layer, PDCP layer, RLC layer, MAC layer and PHY layer all belong to an Access Stratum (AS) layer.

In the second communication method 1200 of the embodiment of the present application, for the terminal device, the corresponding steps are performed by different protocol layers. As shown in fig. 21, S1201 is replaced with step 1e, and the rrc layer also performs step 2e. S1202 is replaced with step 3e to step 5e. The following description of step 1e to step 5e is given below:

step 1e, the RRC layer receives first information from the access network device of the first PLMN.

The first information may be implemented as the above-described information A1, information B1, information C1, or information D1, for example.

Step 2e, the RRC layer sends the first information to the NAS layer. Accordingly, the NAS layer receives the first information from the RRC layer.

And 3e, determining to execute searching of the second PLMN by the NAS layer according to the first information.

Illustratively, when the first information is implemented as information A1, the NAS layer determines that the terminal device is in the area indicated by the information A2 according to the area where the third access network device is located and the information A2. The information A1 includes information of a location area where the third access network device is located, which is described in detail in fig. 13.

When the first information is implemented as the information B1, the NAS layer determines that the terminal device is located in the area indicated by the information B2 according to the location area where the first access network device is located and the information B2. The information B1 includes a location area where the first access network device is located, which is described in detail in fig. 15.

When the first information is implemented as information C1, the NAS layer determines that the PLMN indicated by the second PLMN information belongs to its EPLMN, and determines to search for the second PLMN. The information C1 includes PLMN information of the different network, such as information of the target EPLMN, as described in detail in fig. 18.

When the first information is implemented as the information D1, the NAS layer determines that the PLMN indicated by the second PLMN information belongs to its own HPLMN, and determines to search for the second PLMN. The information D1 includes PLMN information of the foreign network, i.e. HPLMN information, as described in detail in fig. 19.

And 4e, the NAS layer sends the frequency point information of the second PLMN to the RRC layer. Correspondingly, the RRC layer receives the frequency point information of the second PLMN from the NAS layer.

And 5e, the RRC layer searches and resides in the second PLMN according to the frequency point information of the second PLMN.

Illustratively, when the second PLMN is implemented as the target EPLMN, the RRC layer searches for a frequency point of the target EPLMN and then camps on the target EPLMN; when the second PLMN is implemented as an HPLMN, the RRC layer searches for a frequency point of the HPLMN and then resides in the HPLMN, which may be referred to in the related art, and will not be described herein.

The above description has been presented mainly from the point of interaction between the network elements. Correspondingly, the embodiment of the application also provides a communication device, which can be the network element in the embodiment of the method, or a device containing the network element, or a component applicable to the network element. It will be appreciated that the communication device, in order to achieve the above-described functions, comprises corresponding hardware structures and/or software modules performing the respective functions. Those of skill in the art will readily appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

By way of example, fig. 22 shows a schematic structural diagram of a communication device 2200. The communication apparatus 2200 includes a processing unit 2201, a transmitting unit 2202, and a receiving unit 2203.

In a possible example, taking the communication apparatus 2200 as an example of a terminal device, the processing unit 2201 is configured to support the terminal device to perform S704a, S704b, S704c in fig. 7, and/or other processing operations that the terminal device needs to perform in the embodiment of the present application. The sending unit 2202 is configured to support other sending operations that need to be performed by the terminal device in the embodiment of the present application. The receiving unit 2203 is configured to support the terminal device to perform S703 in fig. 7, and/or other receiving operations that the terminal device needs to perform in the embodiment of the present application.

In another possible example, taking the communication apparatus 2200 as an example of a terminal device, the processing unit 2201 is configured to support the terminal device to perform S1202 in fig. 12 and/or other processing operations that the terminal device needs to perform in the embodiment of the present application. The sending unit 2202 is configured to support other sending operations that need to be performed by the terminal device in the embodiment of the present application. The receiving unit 2203 is configured to support the terminal device to perform S1201 in fig. 12, and/or other receiving operations that the terminal device needs to perform in the embodiment of the present application.

In a possible example, taking the communication apparatus 2200 as the first access network device, the processing unit 2201 is configured to support the first access network device to perform S701 and S702 in fig. 7, and/or other processing operations that need to be performed by the first access network device in the embodiment of the present application. The sending unit 2202 is configured to support the first access network device to perform S703 in fig. 7, and/or other sending operations that the first access network device needs to perform in the embodiments of the present application. The receiving unit 2203 is configured to support other receiving operations that need to be performed by the first access network device.

In another possible example, taking the communication apparatus 2200 as an access network device, the processing unit 2201 is configured to support other processing operations that need to be performed by the access network device in the embodiment of the present application. The sending unit 2202 is configured to support the access network device to perform S1201 in fig. 12, and/or other sending operations that the access network device needs to perform in the embodiment of the present application. The receiving unit 2203 is configured to support other receiving operations that need to be performed by the access network device in the embodiment of the present application.

Optionally, the communication device 2200 may further include a storage unit 2204 for storing program codes and data of the communication device, and the data may include, but is not limited to, raw data or intermediate data.

The processing unit 2201 may be a processor or controller, such as a CPU, general purpose processor, application specific integrated circuit (application specific integrated circuit, ASIC), field programmable gate array (field programmable gate array, FPGA) or other programmable logic device, transistor logic device, hardware components, or any combination thereof. Which may implement or perform the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. A processor may also be a combination that performs computing functions, e.g., including one or more microprocessors, a combination of a DSP and a microprocessor, and so forth.

The transmitting unit 2202 may be a communication interface, a transmitter, or a transmitting circuit, where the communication interface is generally called, and in a specific implementation, the communication interface may include multiple interfaces, for example, may include: an interface between a terminal device and an access network device, and/or other interfaces.

The receiving unit 2203 may be a communication interface, a receiver, or a receiving circuit, where the communication interface is generally called, and in a specific implementation, the communication interface may include multiple interfaces, for example may include: an interface between a terminal device and an access network device, and/or other interfaces.

The transmitting unit 2202 and the receiving unit 2203 may be physically or logically implemented as one and the same unit.

The storage unit 2204 may be a memory.

When the processing unit 2201 is a processor, the transmitting unit 2202 and the receiving unit 2203 are communication interfaces, and the storage unit 2204 is a memory, the communication apparatus according to the embodiment of the present application may be as shown in fig. 23.

Referring to fig. 23, the communication device includes: a processor 2301, a communication interface 2302, and a memory 2303. Optionally, the communication device may also include a bus 2304. Wherein the communication interface 2302, the processor 2301 and the memory 2303 may be interconnected by a bus 2304; bus 2304 may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus or an extended industry standard architecture (extended industry standard architecture, EISA) bus, among others. The bus 2304 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in fig. 23, but not only one bus or one type of bus.

Optionally, the embodiments of the present application further provide a computer program product carrying computer instructions that, when run on a computer, cause the computer to perform the method described in the above embodiments.

Optionally, the embodiment of the present application further provides a computer readable storage medium, where the computer readable storage medium stores computer instructions, which when executed on a computer, cause the computer to perform the method described in the above embodiment.

Optionally, an embodiment of the present application further provides a chip, including: processing circuitry and transceiver circuitry for implementing the methods described in the above embodiments. Wherein the processing circuit is used for executing the processing actions in the corresponding method, and the transceiver circuit is used for executing the receiving/transmitting actions in the corresponding method.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, produces a flow or function in accordance with embodiments of the present application, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by a wired (e.g., coaxial cable, fiber optic, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device including one or more servers, data centers, etc. that can be integrated with the available medium. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., digital video disc (digital video disc, DVD)), or a semiconductor medium (e.g., solid state disk (solid state drive, SSD)), etc.

In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or modules, which may be in electrical or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of devices. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

From the above description of the embodiments, it will be clear to those skilled in the art that the present application may be implemented by means of software plus necessary general purpose hardware, or of course by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present application may be embodied essentially or in contributing parts in the form of a software product stored in a readable storage medium, such as a floppy disk, a hard disk, or an optical disk of a computer, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in the embodiments of the present application.

The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and the changes or substitutions within the technical scope of the present disclosure should be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of communication, comprising:

the method comprises the steps that first access network equipment acquires HPLMN information of a home public land mobile network of terminal equipment, wherein the first access network equipment is access network equipment in a PLMN (public land mobile network) to which the terminal equipment is currently accessed, and the PLMN to which the terminal equipment is currently accessed is different from the HPLMN of the terminal equipment;

the first access network device sends first information to the terminal device according to the HPLMN information of the terminal device, wherein the first information is related to the HPLMN of the terminal device, and the first information is used for measurement, HPLMN searching or reselection of the terminal device.

2. The method of claim 1, wherein the first information indicates an HPLMN that initiated a search for the terminal device.

3. The method of claim 1, wherein the first information comprises a cell selection policy;

Wherein the cell selection policy is further related to a current access PLMN of the terminal device;

the measurement configuration information is used for reselection by the terminal equipment.

4. A method according to claim 3, wherein the cell selection policy indicates that the first priority is higher than the second priority, wherein the first priority is the reselection priority of the first cell in the HPLMN of the terminal device and the second priority is the reselection priority of the second cell in the PLMN to which the terminal device is currently accessing.

5. The method of claim 1, wherein the first information comprises measurement configuration information;

the measurement configuration information comprises information of frequency points in the HPLMN of the terminal equipment and information of measurement interval duration of the frequency points;

the measurement configuration information is used for the terminal equipment to measure.

6. The method of claim 5, wherein the frequency points in the HPLMN of the terminal device comprise at least one of:

frequency points of a first communication system in the HPLMN of the terminal equipment;

a frequency point of a second communication system in the HPLMN of the terminal equipment;

wherein the first communication system is different from the second communication system.

7. The method according to any of the claims 1 to 6, wherein the first access network device obtains home public land mobile network, HPLMN, information of the terminal device, comprising:

the first access network device receives a first message from a first core network device, where the first core network device is a core network device in a PLMN to which the terminal device is currently connected, and the first message includes HPLMN information of the terminal device.

8. The method of claim 7, wherein the first message comprises an initial context setup request message.

9. The method according to any of the claims 1 to 6, wherein the first access network device obtains home public land mobile network, HPLMN, information of the terminal device, comprising:

the first access network equipment receives a second message from the terminal equipment, wherein the second message comprises information of the current access PLMN of the terminal equipment, and a corresponding relation exists between the current access PLMN of the terminal equipment and an HPLMN of the terminal equipment;

and the first access network equipment determines the HPLMN information of the terminal equipment according to the second message and the corresponding relation.

10. The method according to any of the claims 1 to 6, wherein the first access network device obtains home public land mobile network, HPLMN, information of the terminal device, comprising:

the first access network device receives a third message from the terminal device, wherein the third message includes HPLMN information of the terminal device.

11. The method according to any one of claims 1 to 6, further comprising:

the first access network device sends a fourth message to a second access network device, where the fourth message includes HPLMN information of the terminal device, the first access network device is the access network device before the terminal device is switched, the second access network device is the access network device after the terminal device is switched, the second access network device and the first access network device belong to the same PLMN, the fourth message is used for the second access network device to send second information based on the HPLMN information of the terminal device, the second information is related to the HPLMN of the terminal device, and the second information is used for the terminal device to perform measurement, HPLMN search or reselection.

12. The method according to any one of claims 1 to 6, further comprising:

the first access network device sends a switching request message to a first core network device, wherein the first access network device is the access network device before the terminal device is switched, and the first core network device is the core network device in the PLMN to which the terminal device is currently connected;

the first core network device sends HPLMN information of the terminal device to a second access network device according to the switching requirement message, wherein the second access network device is the access network device after the terminal device is switched;

and the second access network equipment sends second information to the terminal equipment according to the HPLMN information of the terminal equipment, wherein the second information is related to the HPLMN of the terminal equipment and is used for measurement, HPLMN searching or reselection of the terminal equipment.

13. The method of claim 12, wherein the handover required message includes HPLMN information of the terminal device.

14. The method according to any one of claims 1 to 13, further comprising:

The first access network device receives a measurement report from the terminal device, wherein the measurement report is determined based on the measurement configuration information;

the first access network equipment sends a first message to the terminal equipment, wherein the first message indicates a target cell; the target cell is determined based on the measurement report and priority information, the target cell belongs to a cell in the HPLMN of the terminal device, the priority information indicates that a third priority is higher than a fourth priority, the third priority and the fourth priority are both handover priorities or redirection priorities, the third priority is a priority of a cell in the HPLMN of the terminal device, and the fourth priority is a priority of a cell in the current access PLMN of the terminal device.

15. A method of communication, comprising:

the method comprises the steps that a terminal device receives first information from access network equipment of a first Public Land Mobile Network (PLMN), wherein the first PLMN is a PLMN which is currently accessed by the terminal device, the first information is used for the terminal device to determine to search for a second PLMN, and the first PLMN is different from the second PLMN;

And the terminal equipment searches and resides in the second PLMN according to the first information.

16. The method of claim 15, wherein the first PLMN comprises an HPLMN of the terminal equipment and the second PLMN comprises an equivalent public land mobile network EPLMN of the terminal equipment.

17. The method of claim 16, wherein the method further comprises:

the terminal equipment receives second information from core network equipment of the first PLMN, wherein the second information comprises area information covered by the second PLMN;

the terminal device searches and resides in the second PLMN according to the first information, and comprises:

the terminal equipment determines that the terminal equipment is positioned in an area indicated by the second information according to the area where the access network equipment is positioned and the second information, wherein the first information comprises information of the area where the access network equipment is positioned;

searching and residing in the second PLMN when the terminal device is in the area indicated by the second information.

18. The method of claim 17, wherein the area covered by the second PLMN comprises at least one of:

An overlapping area, where the service area of the core network device overlaps with the coverage area of the second PLMN;

a boundary region, which is a region of the overlap region where a distance from a boundary of the overlap region is smaller than a first threshold;

a first region, which is a region of the boundary region in which a distance from the terminal device is smaller than a second threshold value.

19. The method of claim 18, wherein the terminal device is located within the boundary region or the terminal device is located outside the boundary region.

20. A method according to any of claims 17 to 19, characterized in that the second information is transmitted by the terminal device via an attach accept message or a tracking area update TAU accept message.

21. The method according to any of claims 17 to 19, wherein the second information is transmitted via a user equipment configuration update message.

22. The method of claim 15, wherein the first PLMN comprises an EPLMN of the terminal device and the second PLMN comprises an HPLMN of the terminal device.

23. The method of claim 22, wherein the method further comprises:

The terminal equipment receives second information from core network equipment of the first PLMN, wherein the second information at least indicates a partial coverage area of the first PLMN, and the partial coverage area of the first PLMN belongs to a boundary area of the first PLMN;

24. The method of claim 23, wherein the partial coverage area of the first PLMN comprises at least one of:

an overlapping area, wherein the overlapping area is an area where a service area of the core network device overlaps with a boundary area of the first PLMN;

a first region, which is a region of the overlapping region in which a distance from the terminal device is smaller than a second threshold.

25. The method of claim 17, 18, 23 or 24, wherein the second information is transmitted via a registration accept message.

26. The method according to claim 16 or 22, wherein the terminal device searches for and camps on the second PLMN based on the first information, comprising:

and the terminal equipment searches and resides in the second PLMN according to the second PLMN information, wherein the first information comprises the second PLMN information.

27. The method of claim 26, wherein the terminal device receives the first information from the access network device via a system message.

28. The method of claim 27, wherein the system message carries the first information through a system information block, SIB, wherein the SIB includes at least one of:

the first SIB is used for bearing the same-frequency information, the same-frequency information comprises frequency point information in the second PLMN, and the frequency point in the same-frequency information is the same as the frequency point of the cell where the terminal equipment currently resides;

the second SIB is used for bearing different frequency information, the different frequency information comprises frequency point information in the second PLMN, and the frequency point in the different frequency information is different from the frequency point of the cell where the terminal equipment currently resides;

And the third SIB is used for bearing different system information, the different system information comprises information of a communication system of the second PLMN, and the communication system of the different system information is different from the communication system of the cell where the terminal equipment currently resides.

29. A communication device, comprising: a processor and a memory coupled, the memory storing program instructions that when executed by the processor implement the method of any one of claims 1 to 28.

30. A chip comprising a processor and an input-output interface for receiving signals from or transmitting signals to other communication devices outside the chip, the processor being operable to implement the method of any one of claims 1 to 28 by logic circuitry or executing code instructions.

31. A computer readable storage medium, characterized in that the storage medium has stored therein a computer program or instructions which, when executed by a communication device, implement the method of any of claims 1 to 28.